MULTI-PROJECTILE AMMUNITION AND METHOD OF MAKING

Abstract

A multi-projectile ammunition cartridge has a casing that extends along a central axis to a mouth, the casing having an internal surface and an external surface. An inside surface of the casing adjacent the mouth is parallel to the central axis while the external surface has a slight taper relative to the central axis. Two or more coaxially aligned projectiles are retained within the parallel portion of the casing adjacent the mouth, each projectile having a tapered nose and a rear cavity, where a nose profile of a rearward one of the projectiles differs from the a cavity profile of a forward adjacent one of the projectiles.

Claims

1. A multi-projectile ammunition cartridge, comprising: a casing symmetrical about a central axis and extending along the central axis to a mouth, the casing having an internal surface and an external surface, wherein along a portion of the casing adjacent the mouth the internal surface is parallel to the central axis within 0.002 inch per inch of length, and where the external surface has a taper relative to the central axis; and two or more coaxially aligned projectiles retained within the portion of the casing adjacent the mouth, each projectile having a tapered nose profile and a rear concavity profile, wherein the tapered nose profile of a rearward one of the two or more projectiles differs from the rear concavity profile of a forward adjacent one of the two or more projectiles.

2. The ammunition cartridge of claim 1, wherein each of the two or more projectiles comprises a core of a relatively softer material, the core being at least partially jacketed by a relatively harder material.

3. The ammunition cartridge of claim 2, wherein the relatively softer material comprises lead, lead alloy, tin, tin alloy, zinc, or a zinc alloy.

4. The ammunition cartridge of claim 2, wherein the relatively harder material comprises copper, copper alloy, gilding metal, brass, or steel.

5. The ammunition cartridge of claim 1, wherein the rear concavity profile comprises a surface perpendicular to the central axis.

6. The ammunition cartridges of claim 1, wherein the tapered nose profile of a rearward projectile is partially nested within the rear concavity profile of a forward adjacent one of the two or more projectiles, wherein the general shape of the tapered nose profile and the rear concavity profile are the same, and wherein the tapered nose profile of the rearward one of the two or more projectiles is wider at least at one point than the rear concavity profile of the forward adjacent one of the two or more projectiles.

7. The ammunition cartridge of claim 6, wherein the tapered nose profile of the rearward one of the two or more projectiles is wider than the rear concavity profile of the forward adjacent one of the two or more projectiles due to an angle differential between the tapered nose profile and the rear concavity profile, and wherein an angle of the tapered nose profile with respect to the central axis is greater than an angle of the rear concavity profile with respect to the central axis.

8. The ammunition cartridge of claim 7, wherein the angle differential is from 1 to 20 degrees.

9. The ammunition cartridge of claim 7, wherein the angle differential is from 2 to 15 degrees.

10. The ammunition cartridge of claim 7, wherein the angle differential is from 4 to 10 degrees.

11. The ammunition cartridge of claim 6, wherein the tapered nose profile of the rearward one of the two or more projectiles contacts the rear concavity profile of the forward adjacent one of the two or more projectiles at an annular contact area between the rear concavity and the tapered nose profile, the annular contact area centered on the central axis.

12. The ammunition cartridge of claim 1, wherein the cartridge defines a peripheral air space between the inside surface of the casing, the tapered nose profile of the rearward projectile, and the rear concavity profile of the forward projectile.

13. The ammunition cartridge of claim 12, wherein upon firing, the peripheral air space becomes sealed prior to the two or more projectiles leaving the casing.

14. The ammunition cartridge of claim 1, wherein the internal surface of the casing contacts the two or more projectiles at an annular bearing surface.

15. A method of manufacturing a cartridge case, comprising: forming a metallic cylinder that extends along a central axis from a closed end with a primer pocket to an open end; defining an extractor groove in the cylinder adjacent the closed end; defining a flash opening in the primer pocket, the flash opening aligned with the central axis; forming an exterior taper on an outer surface of the cartridge case; and shaping part of the inside surface of the cylinder adjacent the open end to be parallel to the central axis within an error of not more than 0.002 per inch of length, the part of the inside surface that is parallel having an axial length of at least 1.5 times an interior diameter of the open end.

16. The method of claim 15, further comprising disposing at least one of a primer within the primer pocket and a propellent within the cylinder.

17. The method of any one of claim 15, further comprising disposing two or more axially aligned projectiles within the cylinder and engaged by the inside surface that is parallel to the central axis.

18. The method of claim 17, wherein each of the two or more axially aligned projectiles has a tapered nose profile and a rear concavity profile, wherein the tapered nose profile of a rearward one of the two or more axially aligned projectiles differs from the rear concavity profile of a forward adjacent one of the two or more axially aligned projectiles.

19. The method of claim 15, wherein the error is not more than 0.001 per inch of length.

20. The method of claim 15, wherein the axial length is at least 1.5 times the interior diameter of the open end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 shows a drawing from U.S. Patent no. 703,839 (Scott), in accordance with the prior art.

[0008] FIG. 2 shows a drawing from U.S. Patent no. 1,376,530 (Greener), in accordance with the prior art.

[0009] FIG. 3 shows a drawing from U.S. Patent no. 3,450,050A (Robinson), in accordance with the prior art.

[0010] FIG. 4 is a cross-sectional view of a shoulder-less, generally cylindrical multi-projectile cartridge in assembled form containing partially nested, angular-nose projectiles, in accordance with an embodiment of the present disclosure.

[0011] FIG. 5 illustrates detail C of FIG. 4 and shows air spaces and clearance between partially nested, angular-nose projectiles held in the cylindrical portion of the cartridge case, in accordance with an embodiment of the present disclosure.

[0012] FIG. 6 is a cross-sectional view of a multi-projectile cartridge containing four partially nested projectiles held in the cylindrical portion of the cartridge case, where the rearmost projectile has an enhanced gas-sealing feature, in accordance with an embodiment of the present disclosure.

[0013] FIG. 7 illustrates detail T of FIG. 6 and shows the geometry of the enhanced gas-sealing feature at the back of the rearward-most projectile, in accordance with an embodiment of the present disclosure.

[0014] FIG. 8 is a cross-sectional view of a shoulder-less, generally cylindrical multi-projectile cartridge in assembled form containing four, ogival-shaped, partially nested projectiles with a rear projectile that is longer and heavier than the three projectiles ahead of it, in accordance with an embodiment of the present disclosure.

[0015] FIG. 9 illustrates detail M of FIG. 8 and shows the geometry of the rear projectile that is longer and heavier than the three projectiles ahead of it, in accordance with an embodiment of the present disclosure.

[0016] FIG. 10 is a view of a shoulder-less, generally cylindrical multi-projectile cartridge in assembled form containing ogival-nose projectiles, in accordance with an embodiment of the present disclosure.

[0017] FIG. 11 illustrates detail J of FIG. 10 and shows air space and clearance between partially nested ogival-nose projectiles held in the cylindrical portion of the cartridge case, in accordance with an embodiment of the present disclosure.

[0018] FIG. 12A illustrates an end view of a rifle barrel with an ammunition cartridge in the chamber, in accordance with an embodiment of the present disclosure.

[0019] FIG. 12B illustrates a cross-sectional view of the rifle barrel and ammunition cartridge of FIG. 12A as viewed along line D-D, and shows the ammunition cartridge at the moment the round is fired and four-projectiles leaving the cartridge case as they are driven into the barrel by high-pressure gas, in accordance with an embodiment of the present disclosure.

[0020] FIGS. 13A-13C illustrate detail E of FIG. 12B and show cross-sectional views of a portion of the barrel and four projectiles being driven forward from the explosion and the expanding gas flowing into the rear of the rearward-most projectile and momentarily around the outside of all projectiles, as depicted in broken-line arrows, where the gas is trapped between projectiles as the projectile bases obturate and seal off gas, in accordance with an embodiment of the present disclosure. It should be pointed out at this juncture that the obturating base and wedging action has substantially reduced the air gap between the projectiles, but the projectiles do not become fully nested which prevents them from sticking together upon exit from the muzzle.

[0021] FIG. 14A shows an end view of an ammunition cartridge, in accordance with an embodiment of the present disclosure.

[0022] FIG. 14B is a side view of the ammunition cartridge of FIG. 14A and shows the cartridge case containing four substantially identical projectiles in axial alignment and in direct contact with one another in the cartridge case.

[0023] FIG. 14C is a cross-sectional view of the ammunition cartridge as viewed along line U-U of FIG. 14A.

[0024] FIG. 15 illustrates detail V of FIG. 14C and shows substantially identical projectiles having slightly different diameters and the diameter tolerances associated with each of the numbered projectiles shown, in accordance with an embodiment of the present disclosure.

[0025] FIGS. 16A-16C illustrate a rear-end view, a side view, and a cross-sectional view, respectively, of a projectile with an angled nose and transition between bearing surface and the nose, in accordance with an embodiment of the present disclosure.

[0026] FIGS. 17A-17C illustrate a rear-end view, a side view, and a cross-sectional view, respectively, of a projectile with an angled nose and a secondary shallow-angle transition between the bearing surface and the nose, in accordance with an embodiment of the present disclosure.

[0027] FIGS. 18A-18C illustrate a rear-end view, a side view, and a cross-sectional view of a jacketed projectile with an ogival nose and a shallow rear cavity that provides a better gas seal when an ammunition round is fired, in accordance with an embodiment of the present disclosure.

[0028] FIGS. 19A-19C illustrate a cartridge casing in a rear-end view, a cross-sectional view taken along line A-A of FIG. 19A, and a close-up view of detail B shown in FIG. 19A, in accordance with an embodiment of the present disclosure.

[0029] FIG. 20 is a flow chart illustrating steps in an example method of making an ammunition cartridge, in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

[0030] The present disclosure generally relates to improvements to multi-projectile ammunition and a method of making the same. In one example embodiment, a multi-projectile ammunition cartridge has a one-piece, generally cylindrical cartridge casing that is symmetrical about and extends along a central axis to a mouth. The casing has an internal surface and an external surface. The inside surface of the casing adjacent the mouth is parallel to the central axis while the external surface has a taper relative to the central axis. Along this parallel inside surface, the cartridge casing houses axially aligned, partially nested projectiles of specialized geometry. Two or more coaxially aligned projectiles are retained within the parallel portion of the casing adjacent the mouth, each projectile having a tapered nose profile and a rear concavity profile, where the tapered nose profile of a rearward one of the projectiles differs from the rear concavity profile of a forward adjacent one of the projectiles. In some embodiments, the cartridge houses three or four projectiles.

Overview

[0031] Ammunition containing multiple projectiles is not new. Patents describing various designs based on this concept date back to the 19.sup.th century. One of the earliest approaches is described in U.S. patent no. 703839 issued to Scott in 1902. FIG. 1 reproduces one of the figures from the Scott 839 patent and shows a two-piece, bottleneck cartridge case with three projectiles contained within a very long neck area located at the front end of the cartridge case. The cartridge case utilizes an external shoulder. The projectiles are generally in-line and in direct contact with one another and stacked nose to tail (an arrangement hereinafter referred to as a projectile train). This design and approach results in several problems in use, which are better addressed by the present disclosure. The first drawback is that the cartridges long neck area has a nonstandard dimension, requiring a firearm used in combination with Scotts cartridge to be specially chambered to accommodate the dimensions of the round. A further drawback to Scotts design is that the neck, while elongated, only provides enough room for relatively short projectiles to be disposed within it if the projectiles are not nested. Additionally, the limited room for projectiles cause propellant gasses, when the cartridge is fired, to have less ability to propel the projectiles.

[0032] This loss of propulsion ability compared to the subject application is at least partially due to propellant gas loss around the projectiles, which, in Scotts cartridge, are neither as tightly aligned with the barrel axis as desired, nor configured to obturate or otherwise seal propellant gasses in the manner desired. This may further result in an imbalance of gas pressure between the individual projectiles, as the air spaces defined by the spaces between the projectile and the cartridge wall are imperfectly sealed, even after firing. All of these drawbacks to Scotts method ultimately result in a wider-than-desired cone-of-dispersion (or projectile dispersion) of the projectiles, which may cause all of the projectiles fired from a particular round to entirely miss the intended target.

[0033] Additionally, modern manufacturing capabilities may produce components (such as canisters, projectiles, and firearms) to a far more precise tolerance than the capabilities of the 20.sup.th century. As a result, parameters such as projectile diameter and barrel diameter may be designed with far better alignment than was previously possible. Prior attempts at producing multiplex ammunition have always encountered misalignments between the diameters of individual projectiles. The main problem associated with this degree of projectile misalignment is that inconsistencies in muzzle velocity occur when the round is fired due to (a) above-average gas loss around the stacked projectile train, and (b) an imbalance of gas pressure between the individual projectiles as the projectile train moves through the barrel and as each projectile exits the muzzle.

[0034] As has been made apparent, a major problem when designing multiplex ammunition stems from insufficient sealing of gas in the space behind and between projectiles. The varying amount of gas pressure affects the multi-projectile pattern to an unpredictable and unacceptable degree. The gas imbalance ultimately results in an inconsistent and wider than desired cone of dispersion (radial dispersion) of the projectiles. If the multi-projectile pattern is too wide, then all of the projectiles fired from a particular round can entirely miss the intended target due to excessive space between projectiles. The Scott patent doesnt address the gas loss/gas imbalance problem and Scott doesnt acknowledge that such a problem exists.

[0035] Another early patent, U.S. patent no. 1,376,530, issued to Greener in 1921. FIG. 2 shows a figure from the Greener 530 patent. Greener showed some understanding of the role that gas plays in the propulsion and separation of the projectiles; the reference shows gas spaces shaped into the bodies of rearward projectiles to effect projectile separation when the cartridge is fired. Greener describes various geometries for gas spaces, including a central bore through the axial length of one or more rearward projectiles. In addition to making the projectiles more difficult to manufacture, the gas spaces result in a large decrease in gas pressure at the moment the front-most projectile exits the barrel since the rearward projectiles cannot seal the propellant gases. This pressure drop would result in a different muzzle velocity and trajectory for the rearward projectiles compared to the frontmost projectile, resulting in a wide cone of dispersion.

[0036] A cartridge casing with a long neck and external shoulder was also a common feature of the multiplex ammunition designs that followed many years later, including those produced by and for the U.S. Army during the late 1960s and early 1970s. It should be pointed out that the terms multiplex and multi-projectile are identical in meaning and are therefore interchangeable. Multiplex ammunition containing two projectiles is referred to as duplex ammunition, ammunition containing three projectiles is known as triplex ammunition. Some of the multiplex military ammunition during that era contained more than three projectiles. Many of these multiplex designs suffered from the same neck misalignment, gas loss, and gas imbalance issues between projectiles that plagued earlier designs. Issues which, again, resulted in unpredictably inconsistent and wider than desired patterns. Besides gas variance issues, an additional problem existed as fully nested projectiles situated rearward of the front projectile had a strong proclivity to adhere or stick to each other due to an internal wedging or welding effect as a result of maximum surface area contact between the nose profile or ogive of one projectile and the tightly conforming rear cavity in an axially aligned neighboring projectile. This wedging problem further affected the clean and consistent separation of the projectiles from each other as projectiles exited the muzzle. This inconsistent separation created momentary projectile instability which caused the projectiles to shift off-axis; that is, away from the axis of the barrel in a random manner. This sticking-together problem contributed to a wider downrange pattern than desired.

[0037] A multiplex development during this era that drew broad attention was the Salvo squeeze bore (SSB) system. This concept was patented by Russell Robinson in 1969 (U.S. patent no. 3,450,050) and was further developed by Colt Industries in the late 1960s and early 1970s. FIG. 3 reproduces figures from the Robinson 050 patent. Robinsons system, sometimes called Salvo squeeze bore (SSB), involves a specialized firearm barrel which tapered from being wider at the rear to narrower and rifled at the front. As shown in FIG. 3, which reproduces a drawing from the Robinson patent, the projectiles were fully nested, where the tip of one projectile can be fully received in the recess of the next projectile. The nested projectiles and tapered barrel arrangement functioned to squeeze down projectile diameter prior to encountering the rifling in the barrel. In theory, this squeezing would force the fully nested projectiles to separate from each other after the cartridge was fired but before the projectiles exited the barrel. To accommodate the projectile separation, the system included passages in the projectile skirts to allow gas to fill the spaces formed between projectiles. This approach ultimately failed because there was no ability for a user of an SSB system to consistently control the balance of gas in the barrel and around the projectiles, causing inconsistent firing results from the cartridges. In one of Colts 9 mm tests at a distance of just 47 yards, the radial spread was 42 inches. This was an excessive radial spread with respect to a human-size target at combat ranges normally encountered.

[0038] The U.S. Military did eventually develop a duplex cartridge known as the M198 duplex in 7.62 mm caliber that maintained a tighter radial pattern. But the thrust of the effort was to ensure that the two projectiles would follow meaningfully different trajectories. The M198 Duplex cartridge was ultimately deemed not suitable for Army use due to inaccuracy, reduced penetration and logistical issues. The Army opted for more conventional ammunition designs, such as the M59 Ball cartridge, which provided better performance and reliability. Even before abandonment of the M198 cartridge, a U.S. Army Infantry Board report from 1959 concluded that the T314 (precursor to the M198 duplex cartridge) was not suitable for Army use and did not offer a substantial combat advantage over the standard Ball cartridge (7.62mm NATO M59). The ultimate conclusion at that time was that it did not improve single-shot hit probability to the extent hoped for and was ultimately reclassified as Obsolete (OBS) in the early 1970s. In short, however, the military has never had any real success regarding a middle ground multiplex cartridge that produced an optimal radial pattern at typical combat distances. All of the concepts mentioned above were geared towards engaging human-size targets and were ultimately deemed not suitable for Army use because they didnt offer a substantial combat advantage over the standard, single-round ball cartridge. As a result of these failures, all U.S. Military multiplex ammunition development efforts were discontinued for many years after 1980.

[0039] In light of the previous attempts at multiplex ammunition, many challenges remain. In addition, existing ammunition and previous multiplex ammunition fail to provide an ammunition cartridge suitable for use against Unmanned Aerial Vehicles (UAVs), commonly known as drones. While drones are often much larger than a man-size target, it is difficult to hit fast moving drones using current small caliber weapon platforms when firing single-projectile ammunition. Although shotshell ammunition is readily available and the multiple shot pellets are well suited for hitting moving targets, the pellets are too small to inflict substantial damage to a drone, are too slow, and lose kinetic energy too quickly, which severely limits the effective range of a shotshell-based munition to less than 100 yards. Given the standard operating altitudes of modern combat drones, effective anti-drone ammunition would need to be effective over a much longer rangeanywhere from 200 yards to 1,000 yards or more.

[0040] Given the challenges with previous approaches to multiplex ammunition, it would be desirable to increase hit probability via a higher effective rate of fire using multiple-projectile ammunition due to more projectiles being fired in a given time interval. It would also be desirable to improve multiple-projectile accuracy while controlling the radial cone of dispersion of the projectile cluster over the various ranges encountered. It would also be desirable to inflict greater damage to internal drone components using large diameter projectiles where the projectile diameter is substantially equal to the internal cartridge case diameter. Further, it would be desirable to limit or reduce risk of civilian injury while maintaining the needed effective range.

[0041] The present disclosure addresses these needs and others by providing a multiplex ammunition cartridge as variously disclosed herein. In accordance with some embodiments, a multiplex ammunition cartridge is particularly well suited for use as anti-drone ammunition.

[0042] The present disclosure includes two different feature sets that can be used in tandem to provide multiple projectile ammunition having significantly greater accuracy and consistency, and ultimately provide a more controllable and uniform downrange projectile pattern. The first contributing feature is a shoulder-less (non-bottlenecked), generally cylindrical cartridge case having a slight external taper and a truly cylindrical internal section for accurate and concentric projectile alignment. The bearing surface of each projectile firs tightly and fully against the cylindrical interior section of the case, reducing or minimizing gas pressure loss when the round is fired. In some embodiments, the cartridge case is metal and can be made of either brass or mild steel which is formed (drawn) in stages using a series of precisely machined draw dies. The exterior surface of the cartridge case can have a degree of taper over portions of its length or over its entire length forward of an extractor groove machined into its base. The taper along the exterior surface aids extraction of the case from the chamber when the cartridge is fired. The cartridge case has an interior wall that includes a parallel portion adjacent the mouth that is parallel relative to the axis of the cartridge case. The parallel portion of the cartridge case serves to (a) concentrically align multiple projectiles 14 within this area and (b) minimize premature escape of propellant gases around the projectiles when the cartridge is fired since no air space is present between the interior of the cartridge case and the bearing surface of each projectile. It should be understood that the forward portion of the interior wall in a conventional straight-wall cartridge case is never truly parallel relative to its axis. Precise and accurately machined draw dies are required to form a truly parallel inner surface.

[0043] The second contributing feature is a cartridge with multiple projectiles each having opposed internal and external features and with the ability to seal off expanding gas much quicker and more effectively than prior art projectiles. In some embodiments, the nose of the projectile has a taper that can take various forms. The projectile also has a rear cavity or concavity in its base that has a similar profile, but which is dimensionally different compared to the nose. The dimensional difference between the two profiles results in a partially nested projectile configuration, and ultimately, a partially nested projectile train when all projectiles are in axial alignment with one another. Unlike the cartridge disclosed in the Scott patent, where the tip of one projectile merely contacts the flat, solid base of the projectile ahead of it, the partially nested configuration of the present disclosure automatically aligns the projectiles within the cylindrical section of the cartridge case as the tapered nose of a projectile enters the tapered rear cavity of the projectile ahead of it. This results in a much more concentric projectile train.

[0044] A partially nested configuration differs from prior art multi-projectile ammunition that utilized nested (fully nested) projectiles where the projectile nose of one projectile was in mating contact with all or most of the interior surface of the base recess in the projectile ahead of it. In contrast, projectiles of the present disclosure exhibit a dimensional difference between the two profiles that results in an air space between a portion of the nose of the projectile and a portion of the concavity in the projectile ahead of it.

[0045] Two axially aligned projectiles are partially nested when the nose of a rearward projectile is received in the cavity of the forward projectile, where the nose of the rear projectile contacts the cavity of the forward projectile along a circular or annular surface located at or near the rear end of cavity of the forward projectile, and where the portion of the nose that is forward of the contact surface are spaced axially and radially from the cavity of the forward projectile. In such configuration, the portion of the nose forward of the contact area is spaced axially and radially from the cavity of the forward projectile. Simply stated, due to a difference in dimension between the nose and the cavity (e.g., cone angle or ogive curvature), the nose of the rear projectile does not fit into the cavity of the forward projectile. This geometric relationship results in the partially nested configuration.

[0046] The projectiles (or projectile cores) can be swaged in a conventional manner, pressed using powder metal (PM) technology, machined, or cast. Some or all of the projectiles can be made completely of solid metals like copper, copper alloy, gilding metal, brass, or mild steel. Optionally, some or all of the projectiles can be jacketed, containing a soft, malleable core, if desired. The jacket can be of copper, copper alloy, gilding metal, brass, mild steel or coated or plated steel. The malleable core material can be lead or lead alloy or a lead-free material like tin or a tin alloy, a lead free but less malleable material such as zinc and its alloys, or a frangible material such as bismuth and its alloys. Regardless of the material composition, the projectiles have opposing internal and external geometries that enhance performance when the cartridge is fired by limiting and controlling gas flow within both the cartridge case and the firearm barrel. This enhanced performance is expressed in both the internal and external ballistics of the cartridgethe end result of which is a tighter and more uniform projectile pattern at extended range, in accordance with some embodiments. The opposing geometric features are discussed in more detail below.

[0047] The cartridge can contain two or more projectiles. For purposes of clarity and to provide a more complete understanding of the present disclosure, a cartridge with four projectiles will be described herein and shown in various drawing figures. The four projectiles have been assigned position designations A, B, C, and D as shown in the detail views of the cartridge case and firearm barrel. Note, however, that the cartridge can have more or fewer projectiles. In a four-projectile example, the projectile at position A is positioned at the extreme front of the cartridge case, at the head of the projectile train. Projectile at position D is the rearward-most projectile at the very end or rear of the projectile train. Each projectile has a tapered nose section, a middle cylindrical section (a.k.a., a bearing surface) and a short heel section, preferably comprising an external radius at the projectiles base. If the projectile nose defines an angle (e.g., a conical profile), the concavity within the projectile base can also be conical. If the projectile nose has an ogival profile, the concavity can also have an ogival profile. In either case, the nose profile and the concavity profile of a projectile can be similar in shape, although with different dimensions. In other embodiments, the profile of the nose can be ogival and the profile of the concavity can be conical, or vice versa.

[0048] In some embodiments, the projectile nose can have a shape other than a conical or ogival profile. If the nose consists of any other shape, the profile of the internal cavity can be similar in shape but different dimensionally. From an angle or curvature standpoint this difference between the internal and external interfaces provides the oppositional interference necessary to achieve the goal of superior gas-sealing. In the case of a projectile with a conical nose profile, the surface of the concavity has a different cone angle than that of the nose. For example, the cone angle of the nose is greater than the cone angle of the concavity, thus preventing the tip of the rear projectile from contacting the concavity surface of the projectile ahead of it. In the case of a projectile with an ogival-nose profile, the concavity can have a different radius than that of the nose. For example, the radius along the nose is larger than the radius along the concavity. In the case of any other nose shape or profile, the surface of the concavity can have a similar profile to that of the nose, but the nose profile would be physically larger than that of the concavity, thus preventing the tip of the projectile from making contact with the surface of the concavity of the projectile ahead of it.

[0049] Some of all of the projectiles can have the same nose shape and weight. Optionally, one or two of the projectiles can have a different nose shape and/or weight. For example, the forward-most projectile and/or the rearward-most projectile can have a different nose shape and/or weight than middle projectiles. The reasoning behind the shape and/or weight change involved may be different for each of these projectiles. Changing the nose shape of forward-most projectile, for example, by sharpening its profile, reducing the diameter of its tip or mplat , or increasing its weight can increase the ballistic coefficient (BC) of the projectile, which would flatten its trajectory and alter the downrange patterning of the projectile cluster. Changing its profile in a different way could improve feeding of the cartridge into the barrel of the firearm. A weight increase alone would amplify the gas-sealing ability of projectiles in front of the rearward-most projectile since the additional mass at the front of the projectile train would apply a greater axial force against each of the projectiles when the cartridge is fired, which would in turn create enhanced obturation and a powerful radial gas-sealing effect at the rear of each projectile. The BC of the rearward-most projectile could be increased in the same way stated above.

Example Embodiments

[0050] FIG. 4 shows a cross-sectional view of a multiple projectile cartridge 100 (hereinafter, the cartridge or cartridge) with four projectiles 14A-14D, in accordance with an embodiment of the disclosure. FIG. 5 illustrates an enlarged view of detail C circled in FIG. 4. To avoid obstructing the view of important features of the cartridge case 10 (hereinafter, cartridge case or case), and to enable a clearer understanding of the disclosure, propellant is not shown in the illustrations. The cartridge case 10 has an outside surface 13 with a degree of taper to assist in extracting the cartridge 100 or a fired cartridge case 10 from the chamber of a firearm barrel 20 (e.g., shown in FIG. 12). It should be noted that the rearward portion of the cartridge case 10 is tapered along its interior surface 12, but a forward portion 12a of the interior surface 12 adjacent the mouth 11 is parallel to the axis 2 of the cartridge 100.

[0051] The parallel portion 12a of the cartridge case 10 serves to (a) concentrically align multiple projectiles 14 within this area and (b) minimize premature escape of propellant gases around the projectiles 14 when the cartridge 100 is fired since no air space is present between the interior of the cartridge case 10 and the bearing surface 22 of each projectile 14. It should be understood that in a conventional straight-wall cartridge the forward portion of the interior wall is never truly parallel relative to its axis. Precise and accurately machined draw dies are required to form a truly parallel inner surface.

[0052] Each projectile has a tapered nose 16, a middle cylindrical section (a.k.a., a bearing surface) 22 and a short heel section 31, preferably comprising an external radius at the base 32 of the projectile 14. If the projectile nose 16 defines an angle (e.g., having a conical profile), the concavity 18 within the projectile 14 base 32 can also be conical. If the projectile nose 16 has an ogival profile, the concavity 18 can also have an ogival profile. In either case, the nose profile and the concavity profile of a projectile 14 can be similar in shape, although with different dimensions. In other embodiments, the profile of the nose can be ogival and the profile of the concavity 18 can be conical, or vice versa.

[0053] As mentioned above, each projectile 14 has a tapered nose section 16 that can consist of an angle, an ogival shape or any other shape desired. And each projectile 14 can have a rear cavity 18 formed in its base which can consist of an angled or an ogival shape, or any other shape. In the case of a projectile 14 having an angled nose profile, the profile of the rear cavity 18 may also comprise an angle. However, the nose angle is greater than the rear cavity angle, to maintain an air space C between the nose 16 and the concavity 18. The mismatched angles (i.e., dissimilar angles) constitutes the opposing geometries mentioned above.

[0054] Projectile 14D can be considered the first line of defense with respect to the sealing off of a volume of expanding gas in the cartridge case 10 at the moment the cartridge is fired. When the cartridge is fired, the base 32 of projectile 14D obturates by flaring radially outwardly, sealing off a portion of the expanding gas. At the same time, the conical nose 16 of the rearward-most projectile 14D is violently driven into the rear cavity 18 of projectile 14C ahead of it, which applies a much greater radial flaring force on its base 32 than that produced in the rearward-most projectile 14D. This results in much more efficient obturation (and subsequent radial outward force) due to the powerful wedging effect generated. At this point the bulk of the gas has been sealed off, but the cycle continues as projectile 14C penetrates the open base 32 of projectile 14B and projectile 14B penetrates the open base 32 of the forward-most projectile 14A, adding to an overall more consistent sealing effect. Because this mass obturation effect occurs simultaneously, very quickly (in a fraction of a millisecond), and so efficiently, very little gas blow-by (gas escaping around the outside of the projectile train and into the barrel 20) results. More importantly, a much smaller and more uniform volume of gas is trapped and quickly sealed off in space A between projectiles 14 than is possible with any of the prior art ammunition.

[0055] Unlike fully nested projectiles of the prior art, which have a strong proclivity to adhere or stick to each other due to an internal welding effect that results from maximum surface area contact between the nose of one projectile and the conforming rear cavity of the next, the partially nested projectiles 14 of the present disclosure limit the axial penetration of the projectile nose 16 into the rear cavity 18 of the projectile ahead of it due to the opposing angles involved, thus reducing the area of contact and adhesion. This localized and self-limiting wedging effect ultimately allows the projectiles 14 to break free from each other more quickly and more cleanly upon exiting the muzzle due to reduced frictional resistance. Tighter, more symmetrical patterns develop downrange due to these advantages. It should be pointed out that a major reason the dissimilar or mismatched angle approach has such a powerful radial effect is that a cone (e.g., the general shape of the projectile nose 16) is a modified form of a simple machine (the wedge), and simple machines make work easier. The work involved here is the penetration and deformation of the heel 31 area of a neighboring projectile 14. This radial deformation force can be amplified by increasing the nose angle 1 (making it less sharp), but increasing the nose angle 1 to an excessive degree significantly reduces the projectile's BC and moves its Center of Gravity (COG). Increasing the nose angle 1 will affect projectile 14 length. Under certain projectile 14 design conditions, such as a projectile 14 having a small inner diameter at the opening of the rear cavity 18, projectile length is increased. This occurs because the increased nose angle 1wont allow a projectile to penetrate the rear cavity 18 of the bullet in front of it as deeply since the cavity angle 2 is smaller than the nose angle 1. Increased bullet length would result in a greater projectile train length. A lengthened projectile train would reduce cartridge case 10 capacity (e.g., because the case would hold less propellant) and this would ultimately reduce muzzle velocity. While the angle differential between the nose angle 1 and the cavity angle 2 could be quite small, in order to strike a balance between obturation efficiency and projectile train length, the difference is not greater than 15 degrees in some embodiments. For example, the difference between 1 and 2 is between 4 degrees and 10 degrees.

[0056] FIG. 5 illustrates detail C of FIG. 4, showing the forward portion of the case 10 containing the projectiles 14. The projectile nose 16 projects forwardly of the mouth 11 of the cartridge case 10. The forward portion 12a of the case inside surface 12 that is parallel to the axis 2 extends rearwardly from the mouth 11 at least to include the bearing surface 22 of the rearward-most projectile 14D. As noted above, the parallel forward portion 12a serves to concentrically align the multiple projectiles 14 within this area and minimize the premature escape of propellant gas pressure GP (shown in FIG. 13B) around the projectiles 14 when the cartridge 100 is fired. Since the forward portion 12a is parallel to the case axis 2, no air space is present between the interior surface 12a of the cartridge case 10 and the bearing surface 22 (FIG. 13) of each projectile 14 prior to the cartridge 100 being fired. Air spaces A exist between the base 32 of one projectile 14 and the nose 16 of the projectile behind it. A clearance C gap also exist between the nose 16 of one projectile 14 and the concavity 18 of the projectile 14 ahead of it (i.e., a partially nested configuration). A portion of the clearance C shown here is maintained even after the cartridge 100 is fired and the projectile train is shortened. This clearance C, in combination with a more uniform volume of trapped gas within the air spaces A, allows an easier, cleaner release of the individual projectiles 14 from each other as they exit the muzzle. A clean release of the individual projectiles 14 from each other achieves a tight and uniformly spaced downrange projectile pattern. Erratic and inconsistent projectile release from one another upon exit from the muzzle and the subsequent poor patterning has been a heretofore unsolvable problem.

[0057] Referring now to FIG. 6, a longitudinal section shows a cartridge 100 with four projectiles 14, in accordance with another embodiment of the present disclosure. FIG. 7 illustrates detail T of FIG. 6. The nose 16 of each projectile 14 has a linear taper or angled profile. The rearward-most projectile 14D has an enhanced gas-sealing feature of a thinned (weakened) area 24 in the heel region 32. Specifically, the radial wall thickness T at the base 32 adjacent the rear cavity 18 of the rearward-most projectile 14D can be reduced in some embodiments, making the wall of the projectile 14 weaker and therefore more radially deformable, which can provide quicker, more aggressive obturation and subsequently an even more efficient gas-sealing effect. The radial wall thickness T can be, for example, from 0.008 inch to 0.060 inch. The reduced radial wall thickness T is advantageous since the rear cavity 18 of the rearward-most projectile 14D is directly acted upon only by the expanding gas created by the explosion when the cartridge is fired. In other words, rearward-most projectile 14D doesnt enjoy the mechanical advantage afforded by the conical wedging/gas-sealing effect experienced by projectiles 14A-14C, namely, a tapered projectile nose 16 behind it being driven into the rear cavity 18.

[0058] Referring now to FIG. 8, a longitudinal section illustrates a cartridge 100 with four projectiles 14A-14D in a projectile train, in accordance with another embodiment. FIG. 9 illustrates detail M as shown in FIG. 8. In this example, the nose 16 of each projectile 14 has an ogival profile. Like the mismatched angle principle discussed above, a similar, but somewhat reduced radial deformation effect and limited axial penetration can be achieved using mismatched radii based on the ogive radius of the projectile nose 16. As in the case of mismatched angles, the ogive radius R1 of the nose 16 is larger than the radius R2 of the rear cavity 18, such as shown in projectile 14A of FIG. 9. The radius differential can be as small as 0.010 inch but should be no larger than 1 inch, in some embodiments. However, it should be pointed out that if the center points of the radii relative to each other are offset, the radius differential can be zero. With respect to any other nose profile or shape, the same principle associated with nose angles and nose ogives holds true: the profile of the nose 16 is larger than the profile of the rear cavity 18.

[0059] In the example of FIG. 9, the rearward-most projectile 14D is longer and heavier than the projectiles 14A-14C forward of it. This increased size and mass results in an increase in BC for the larger rearward-most projectile 14D. The increased momentum from propelling a larger rearward-most projectile 14D will also have the effect of increasing the obturation of the projectile 14C forward of the rearward-most projectile 14D, due to a more powerful conical wedging effect. It should be noted that, although this figure shows the rearmost projectile 14D as the longer and heavier one, any one or more of the projectiles 14 may be larger, smaller, or different with respect to the other projectiles. The forward-most projectile 14A being longer and heavier with respect to the other projectiles 14 will result in a higher BC just as it does for the rearward-most projectile 14D when it is longer and heavier. Varied BCs may alter the downrange projectile pattern of the projectiles. Varied arrangements of sized projectiles may be used to achieve a users ideal BC, and therefore downrange pattern, for their particular application.

[0060] FIG. 9 shows a shallow rear cavity 18 in the base 32 of the rearward-most projectile 14D and a thinned (weakened) area 24 near the heel 31 of the same projectile to provide enhanced gas sealing. Providing a heavier rearward-most projectile 14D will increase the projectiles BC which could alter the downrange patterning of the projectile cluster in a positive way.

[0061] To further enhance obturation in some embodiments, the projectile material itself, and/or the core material in the case of a jacketed projectile 14, can be softer. In some embodiments, such as shown in FIGS. 8-9, the thinned area 24 of the heel 31 region noted above can be applied by creating a shallow rear cavity 18, which creates a folded, more easily deformable lip to enhance and expedite obturation. The jacket 28 (e.g., shown in FIG. 18), if present, can also be specifically annealed to make it softer as well.

[0062] FIG. 10 shows a cross-sectional view of a multiple-projectile cartridge 100 of the present disclosure containing 4 partially nested projectiles 14 held in a cylindrical portion of the cartridge case 10. FIG. 11 shows detail J of FIG. 10, showing the parallel portion 12a of the case 10 containing the projectiles 14. In this example, the projectiles 14 have an ogival- shaped nose 16, and are configured to partially nest within one another, such that small clearances C exist between the nose 16 of a rearward projectile 14 and the concavity 18 of a forward projectile 14. An air space A exist between the parallel portion 12a of the case 10 and projectiles 14 adjacent the heel 32, where the space A is axially between the heel 32 of one projectile 14 and the nose 16 adjacent the bearing surface 22 of a projectile 14 behind it. Adjacent projectiles 14 contact each other at an annular contact area forming the boundary between the clearances C and the air spaces A.

[0063] FIG. 12A shows an end view and FIG. 12B shows a cross-sectional view of a rifle barrel 20 as viewed along line D-D of FIG. 12A, where the barrel 20 contains a cartridge 100 of the present disclosure at the moment the round is fired. FIG. 12B shows four-projectiles 14A-14D leaving the cartridge case 10 as they are being driven into the barrel 20 by high-pressure gas. Each of the projectiles 14 is axially aligned, such that the nose 16 of each projectile 14 is driven into the center of the heel 32 of the projectile 14 forward of it. This alignment can be further seen by examining line D-D, which shows the concentricity of the projectiles 14. This driving action has forced the forward projectiles to obturate, thereby providing enhanced sealing of propellant gasses and preparing the projectiles 14 to engage with the rifling 21 toward the front of the barrel 20 which is depicted in the figure. After the cartridge is fired, but before the projectiles 14 exit the barrel 20, the clearance between the nose 16 of a rearward projectile 14 and the rear cavity 18 of a forward projectile 14 is compressed but not eliminated. The air spaces A peripheral to each projectile 14 are impacted in much the same way. The preservation of these air spaces A and clearances C (shown in FIG. 11) helps to guide the projectiles 14 out of the barrel 20 when fired, as well as to separate the projectiles 14 once they exit the barrel 20. The compression of the clearances C and air spaces A is accomplished primarily by the obturation action of the projectiles 14 when fired, which, alongside sealing the heels 32 of the projectiles 14 against propellant gasses, also more perfectly seals the clearances C and air spaces A in the barrel 20, ensuring the projectiles 14 separate in flight in a more consistent manner.

[0064] FIGS. 13A-13C show detail E of FIG. 12B, depicting a firearm barrel 20 after the cartridge 100 has been fired. Depicted on the barrel is rifling 21 with a groove diameter G. Gas pressure GP of expanding propellant gas has driven the four projectiles 14A-14D out of the cartridge case 10 and into the throat portion of the barrel 20 which lies forward of the case mouth 11. FIG. 13B depicts the high-speed activity taking place as expanding gas pressure GP interacts with these projectiles 14. Gas pressure GP flow is represented by broken lines and is shown here flowing from left to right. The expanding gas pressure GP has filled the rear cavity 18 of the rearward-most projectile 14D and has driven that projectile 14D forward into projectile 14C, which in turn drove projectile 14C into projectile 14B, and drove projectile 14B into the forward-most projectile 14A. This action creates powerful radial forces due to a violent outward wedging action, where such forces are greater than the force of gas pressure GP acting on the rearward-most projectile 14D. At the same time, gas flows around and past each of the projectiles 14 and has filled the former air spaces A between projectiles 14 with trapped gas TG. Prior to totally sealing off all of the gas, a small volume of gas inevitably passed into the barrel 20. In a very brief moment in time (a fraction of a millisecond), the entire projectile train has been compressed axially as the nose 16 of each of projectiles 14B-14D has been driven into the rear cavity 18 of the projectiles 14A-14C ahead of it, respectively. This produces an exceptionally quick and effective sealing action and reduces the clearance C between a projectile nose 16 and the rear cavity 18 of the projectile 14 ahead of it. Note, however, that the clearance C remains between adjacent projectiles 14 upon and after firing. The combination of a more uniform volume of trapped gas TG and the ease by which the projectiles 14 can break free from each other upon exit from the muzzle due to clearance C allows tighter and more uniform down range patterns.

[0065] FIGS. 14A-14C show multiple views of a shoulder-less, generally cylindrical multi-projectile cartridge 100 in assembled form containing angled-nose projectiles 14, in accordance with an embodiment of the present disclosure. FIG. 14A is an end view of a cartridge 100; FIG. 14B is a side view of the cartridge 100; and FIG. 14C is a cross-sectional view of the cartridge 100 as viewed along line U-U of FIG. 14A. In this example, the projectiles 14 have a nose 16 with a conical or angled profile, and a concavity 18, which is of the same type of profile (e.g., ogival or conical), but of different angle, resulting in partially nested projectiles. As a result of the different dimensions between the nose 16 and concavity 18, air spaces A exist between the rear portions of projectiles 14A-14C. A clearance C exists between the nose 16 and concavity 18 of adjacent projectiles.

[0066] FIG. 15 shows detail V of FIG. 14C, a view of the cylindrical portion 12a of the cartridge case 10 showing the preferred projectile diameter tolerances associated with each of the four projectiles 14A-14D, in accordance with an embodiment of the present disclosure. The parallel portion 12A of the inside surface 12 has an inner diameter ID that is the same as the groove diameter G of the barrel (within manufacturing tolerances). Each of the projectiles 14 has an outer diameter. The projectile 14 diameter can be the same for all projectiles 14 if desired. However, it is preferred that the projectiles 14 specifically have different diameters so that when the rearward-most projectile 14D is inserted into the cartridge case 10 atop the propellant charge (not shown), it doesnt unduly expand the inner diameter of the entire parallel section 12a of the cartridge case 10 which could loosen the radial grip of the case 10 on the balance of the projectile train, and therefore the remaining projectiles. In keeping with this safeguard, projectile 14D can have the smallest diameter of all of the projectiles 14. The same basic diameter scheme holds true for middle projectiles 14C and 14B, where projectile 14C is larger than projectile 14D and projectile 14B is larger than projectile 14C. This progressive dimension scheme is presented in percentage form based on the groove diameter G of the barrel 20 as shown by double arrows.

[0067] In one example, the diameter of the rearward-most projectile 14D can be between 0.2% and 0.3% smaller than the barrels 20 groove diameter G (e.g., 0.997G to 0.998G), projectile 14C can have a diameter between 0.1% and 0.2% smaller than groove diameter G (e.g., 0.998G to 0.999G), projectile 14B can have a diameter that is up to 0.1% smaller than groove diameter G (e.g., 0.999G to G) and the forward-most projectile 14A can have a diameter that is up to 0.1% larger than groove diameter G (e.g., G to 1.001G). The larger diameter of the forward-most projectile 14A can be particularly important. For example, the outer diameter of the forward-most projectile 14A is larger than the other projectiles so that the radial grip of the case 12 on it is maximized to ensure that projectile 14A remains securely in place and cant move axially as a result of feed ramp impact or an adverse inertial effect as a result of weapon recoil. In short, sufficient bullet pull is required to secure the forward-most projectile 14A in the case 10. Bullet pull is the force required to extract or pull the projectile 14 from a cartridge case. As an example, the bullet pull requirement for the .50 BMG cartridge is 200 pounds. To further increase the bullet pull in the cartridge 100 of the present disclosure, a circumferential groove (a cannelure, not shown) can be created on the bearing surface 22 of projectile 14A, if desired, and a crimp (not shown) can be applied to the mouth 11 of the cartridge case 10.

[0068] FIGS. 16A, 16B, and 16C illustrate a rear-end view, a side view, and a cross-sectional view taken along line F-F, respectively, of a projectile 14 having an angled nose 16 and concavity 18, in accordance with an embodiment of the present disclosure. The bearing surface 22 of any of the projectiles 14 of the present disclosure can be wider or narrower than shown. By the same token, the projectile nose 16 can be longer or shorter than that shown, regardless of the contour of the nose 16 (e.g., angled or ogival). Additionally, the mplat 30 can be larger or smaller than that shown and can have different profiles, such as rounded, flat, or recessed. As should be apparent from the present disclosure, the projectiles 14 may be formed from a number of materials selected for their particular ballistic or impact properties. Line F-F serves to illustrate the symmetry of the projectile and the concentricity of a potential projectile train. It is the geometry of the projectile 14 which allows the obturation and wedging actions that enable the functions of the present disclosure.

[0069] FIGS. 17A, 17B, and 17C illustrate a rear-end view, a side view, and a cross-sectional view taken along line G-G, respectively, of a projectile 14 having an angled nose 16 and concavity 18, in accordance with an embodiment of the present disclosure. The mplat 30 is illustrated as rounded in this example.

[0070] FIGS. 18A, 18B, and 18C illustrate a rear-end view, a side view, and a cross-sectional view taken along line Q-Q, respectively, of a projectile 14 having an ogival nose 16, in accordance with an embodiment of the present disclosure. In this example, the projectile 14 has a jacket 28 over a malleable core 26. The projectile 14 also features a shallow rear cavity 18 in its base 32 along with a readily deformable thinned area 24 at the heel 31 to enhance obturation and to provide superior gas sealing. The jacket 28 can be copper, gilding metal, brass, or mild steel. The malleable core 26 material can be lead or lead alloy or a lead-free material like tin or a lead free but less malleable material such as zinc and its alloys, or a frangible material such as bismuth and its alloys. As should be apparent from the present disclosure, the projectiles 14 may be formed from a number of materials selected for their particular ballistic or impact properties. Line Q-Q serves to illustrate the symmetry of the projectile and the concentricity of a potential projectile train. It is the geometry of the projectile 14 which allows the obturation and wedging actions that enable the functions of the present disclosure.

[0071] FIGS. 19A-19C illustrate a cartridge casing 10 in a rear-end view, a cross-sectional view taken along line A-A of FIG. 19A, and a close-up view of detail B shown in FIG. 19A, in accordance with an embodiment of the present disclosure. The cartridge casing 10 extends along a central axis 2 to a mouth 11 and has an inside surface 12 and an outside surface 13. Adjacent the mouth 11, the casing 10 the inside surface 12 includes a parallel portion 12a that is parallel to the central axis 2. Preferably, the parallel portion 12a is truly parallel to the central axis 2; in some embodiments, however, the parallel portion 12a can have a diametrical taper of up to 0.002 per inch of length L, including a taper of not more than 0.0015, not more than 0.001 and not more than 0.0005 per inch of length L. Stated differently, the parallel portion 12a can have an inner diameter from G-0.3% to G+0.1%, in accordance with some embodiments.

[0072] In some embodiments, the parallel portion 12a has an axial length L that is 1.5 to 3 times the groove diameter G (1.5G L 3G). In some embodiments, the parallel portion 12a has an axial length L of twice the groove diameter 5, namely, 2G. Other values within this range are acceptable, including 1.75G, 2.25G, 2.5G, and 2.75G. Note that rearward of the parallel portion 12a that the inside surface 12 tapers radially inward as it approaches the proximal end 15 of the casing 10, thus resulting in a greater wall thickness near the proximal end 15.

[0073] In some embodiments, the outside surface 13 of the casing 10 has a diametrical taper of 0.005 to 0.025 per inch of axial length, including from 0.005 to 0.018. The casing 10 can have an overall case length in a range of 3G to 8G, depending on the caliber. In some embodiments, the overall case length is in a range from 4.5G to 6.5G. In one embodiment, the casing 10 has an overall length of about 3.27 inches or 6.4G.

[0074] FIG. 19 is a flow chart illustrating steps in an example method 300 of making a multi-projectile cartridge, according to an embodiment of the present disclosure. Manufacture of the cartridge case begins by blanking a circular disk from metal coil (e.g., brass) and then forming 310 the disk into a cylinder having a closed end and an open end. Process 310 can include annealing the cylinder, deep drawing the cylinder, annealing the cylinder, deep drawing the cylinder, annealing the cylinder, and again deep drawing the cylinder. The metallic cylinder can comprise any of the metals noted above as possibilities for the makeup of the cartridge case.

[0075] Method 300 continues with turning or otherwise defining 315 an extractor groove adjacent a head of the casing. Method 300 continues with defining 320 a flash opening. In some embodiments, process 320 includes defining a primer pocket, piercing or otherwise defining a flash opening, and performing a localized anneal.

[0076] Method 300 continues with forming 325 an exterior taper on the cartridge case, followed by forming 330 a cylindrical interior cavity adjacent the mouth of the case. Method 300 optionally includes trimming the cartridge case and performing a localized anneal before inserting 330 a primer and propellant into the case. Finally, method 300 continues with sequentially installing 340 a plurality of projectiles in the parallel portion of the casing.

[0077] The steps of method 300 are presented and described sequentially. However, the steps of method 300 may be performed out of the order presented. For example, once a cylinder is formed, whether the primer pocket or the extractor groove is next formed is immaterial, so long as both elements are formed before projectiles are installed.

Further Example Embodiments

[0078] The following examples pertain to embodiments of the technology disclosed herein, from which numerous permutations and configurations will be apparent.

[0079] Example 1 is a multi-projectile ammunition cartridge. The cartridge has a casing symmetrical about a central axis and extending along a central axis to a mouth. The casing has an internal surface and an external surface, where along a portion of the casing adjacent the mouth the internal surface is parallel to the central axis within an error of 0.002 inch per inch of length, and where the external surface has a taper relative to the central axis. Two or more coaxially aligned projectiles are retained within the portion of the casing adjacent the mouth, each projectile having a tapered nose profile and a rear concavity profile. The tapered nose profile of a rearward one of the two or more projectiles differs from the rear concavity profile of a forward adjacent one of the two or more projectiles.

[0080] Example 2 includes the cartridge of Example 1, where each of the two or more projectiles comprises a solid metal.

[0081] Example 3 includes the cartridge of Example 2, where the solid metal comprises copper, a copper alloy, gilding metal, brass, or steel.

[0082] Example 4 includes the cartridge of any one of Examples 1-3, where each of the two or more projectiles comprises a core of a relatively softer material, the core being at least partially jacketed by a relatively harder material.

[0083] Example 5 includes the cartridge of Example 4, where the relatively softer material comprises lead, lead alloy, tin, tin alloy, zinc, or a zinc alloy.

[0084] Example 6 includes the cartridge of Example 4 or 5, where the relatively harder material comprises copper, copper alloy, gilding metal, brass, or steel.

[0085] Example 7 includes the cartridge of any one of Examples 1-6, where each of the two or more projectiles comprises a frangible material.

[0086] Example 8 includes the cartridge of any one of Examples 1-7, where the tapered nose profile is ogival.

[0087] Example 9 includes the cartridge of any one of Examples 1-7, where the tapered nose profile is conical.

[0088] Example 10 includes the cartridge of any one of Examples 1-9, where the tapered nose profile culminates in a mplat.

[0089] Example 11 includes the cartridge of any one of Examples 1-10, where the rear concavity profile is ogival.

[0090] Example 12 includes the cartridge of any one of Examples 1-10, where the rear concavity profile is conical.

[0091] Example 13 includes the cartridge of any one of Examples 1-12, where the rear concavity profile comprises a surface perpendicular to the central axis.

[0092] Example 14 includes the cartridge of any one of Examples 1-13, where the tapered nose profile of a rearward projectile is partially nested within the rear concavity profile of a forward adjacent one of the two or more projectiles, where the general shape of the tapered nose profile and the rear concavity profile are the same, and where the tapered nose profile of the rearward one of the two or more projectiles is wider at least at one point than the rear concavity profile of the forward adjacent one of the two or more projectiles.

[0093] Example 15 includes the cartridge of Example 14, where the rearward one of the two or more projectiles is wider due to an angle differential between the tapered nose profile and the rear concavity profile, and where an angle of the tapered nose profile with respect to the central axis is greater than an angle of the rear concavity profile with respect to the central axis.

[0094] Example 16 includes the cartridge of Example 15, where the angle differential is from 1 to 20 degrees.

[0095] Example 17 includes the cartridge of Example 16, where the angle differential is from 2 to 15 degrees.

[0096] Example 18 includes the cartridge of Example 16, where the angle differential is from 4 to 10 degrees.

[0097] Example 19 includes the cartridge of any one of Examples 14-18, where the tapered nose profile of the rearward one of the two or more projectiles contacts the rear concavity profile of the forward adjacent one of the two or more projectiles at an annular contact area between the rear concavity and the tapered nose profile and centered on the central axis.

[0098] Example 20 includes the cartridge of any one of Examples 1-19, where the cartridge defines a peripheral air space between the inside surface of the casing, the tapered nose profile of the rearward projectile, and the rear concavity profile of the forward projectile.

[0099] Example 21 includes the cartridge of Example 20, where the peripheral air space is sealed.

[0100] Example 22 includes the cartridge of Example 20, where upon firing, the peripheral air space becomes sealed prior to the two or more projectiles leaving the casing.

[0101] Example 23 includes the cartridge of any one of Examples 1-22, where the two or more projectiles includes at least three projectiles.

[0102] Example 24 includes the cartridge of Example 23, where the two or more projectiles includes at least four projectiles.

[0103] Example 25 includes the cartridge of any one of Examples 1-24, where the internal surface of the casing contacts the two or more projectiles at an annular bearing surface.

[0104] Example 26 is a multi-projectile cartridge comprising a straight-wall casing symmetrical about a central axis and extending along a central axis to a mouth, and two or more coaxially aligned projectiles retained within the casing adjacent the mouth, where at least one of the two or more projectiles has an incongruency with respect to the rest of the two or more projectiles. The incongruency is selected from one or more of a projectile diameter, a projectile mass, a projectile shape, and a projectile construction.

[0105] Example 27 includes the cartridge of Example 26, where the incongruency is in a frontmost projectile.

[0106] Example 28 includes the cartridge of Example 26, where the incongruency is in a rearmost projectile.

[0107] Example 29 includes the cartridge of any one of Examples 27 or 28, where each of the two or more projectiles has a tapered nose profile, and the incongruency is a different tapered nose profile.

[0108] Example 30 includes the cartridge of any one of Examples 27 or 28, where each of the two or more projectiles has a rear concavity profile and the incongruency comprises a different rear concavity profile among the at least two or more projectiles.

[0109] Example 31 includes the cartridge of Example 28, where each of the two or more projectiles has a rear concavity profile and where the incongruency comprises a different rear concavity profile in a rearward-most projectile of the two or more projectiles.

[0110] Example 32 includes the cartridge of any one of Examples 26-31, where each of the two or more projectiles is different from all other projectiles of the two or more projectiles.

[0111] Example 33 includes the cartridge of Example 32, where a projectile diameter differs among the two or more projectiles.

[0112] Example 34 includes the cartridge of Example 33, where the two or more projectiles are arranged by diameter inside the casing, with a frontmost projectile having a largest diameter and a rearmost projectile having a smallest diameter.

[0113] Example 35 includes the cartridge of any one of Examples 26-34, where each of the two or more projectiles comprises a metal selected from copper, a copper alloy, gilding metal, brass, or steel.

[0114] Example 36 includes the cartridge of any one of Examples 26-35, where each of the two or more projectiles comprises a core of a relatively softer material, the core being at least partially jacketed by a relatively harder material.

[0115] Example 37 includes the cartridge of Example 36, where the relatively softer material comprises lead, lead alloy, tin, tin alloy, zinc, or a zinc alloy.

[0116] Example 38 includes the cartridge of any one of Examples 36 or 37, where the relatively harder material comprises copper, copper alloy, gilding metal, brass, or steel.

[0117] Example 39 includes the cartridge of any one of Examples 26-38, where each of the two or more projectiles comprises a frangible material.

[0118] Example 40 includes the cartridge of any one of Examples 26-39, where the tapered nose profile is an ogival profile.

[0119] Example 41 includes the cartridge of any one of Examples 26-39, where the tapered nose profile is conical.

[0120] Example 42 includes the cartridge of any one of Examples 26-41, where the tapered nose profile culminates in a mplat.

[0121] Example 43 includes the cartridge of any one of Examples 26-42, where the rear concavity profile includes an ogival profile.

[0122] Example 44 includes the cartridge of any one of Examples 26-42, where the rear concavity profile includes a conical profile.

[0123] Example 45 includes the cartridge of any one of Examples 26-44, where the rear concavity profile includes a surface perpendicular to the central axis.

[0124] Example 46 includes the cartridge of any one of Examples 41-45, where the tapered nose profile of a rearward projectile is partially nested within the rear concavity profile of a forward projectile, and where the tapered nose profile of the rearward projectile is wider at least at one point than the rear concavity profile of the forward projectile.

[0125] Example 47 includes the cartridge of Example 46, where the rearward projectile is wider due to an angle differential between the tapered nose profile and the rear concavity profile.

[0126] Example 48 includes the cartridge of Example 47, where the angle differential is from 1 to 20 degrees.

[0127] Example 49 includes the cartridge of Example 47, where the angle differential is from 2 to 15 degrees.

[0128] Example 50 includes the cartridge of Example 47, where the angle differential is from 4 to 10 degrees.

[0129] Example 51 includes the cartridge of any one of Examples 46-50, where the tapered nose profile of the rearward projectile contacts the rear concavity profile of the forward projectile at an annular contact area centered on the central axis.

[0130] Example 52 includes the cartridge of any one of Examples 46-51, where the assembly defines a peripheral air space along the casing between the tapered nose profile of the rearward projectile and the rear concavity profile of the forward projectile.

[0131] Example 53 includes the cartridge of Example 52, where the peripheral air space is sealed between the casing, the annular contact area, a bearing surface of the rearward projectile, and a bearing surface of the forward projectile.

[0132] Example 54 includes the cartridge of any one of Examples 26-53, where the two or more projectiles includes at least three projectiles.

[0133] Example 55 includes the cartridge of any one of Examples 26-53, where the two or more projectiles includes four projectiles.

[0134] Example 56 is a multi-projectile ammunition round comprising a casing symmetrical about a central axis and extending along a central axis to a mouth, and two or more coaxially aligned and partially nested projectiles disposed within the casing. Each projectile has a tapered nose profile with a tip and a rear concavity profile with a base. The tapered nose profile of a rearward projectile of the two or more projectiles differs from the rear concavity profile of an adjacent forward projectile of the two or more projectiles such that the tip of the rearward projectile is axially spaced from the rear concavity profile of the adjacent forward projectile.

[0135] Example 57 includes the ammunition round of Example 56, where the tapered nose profile of the rearward projectile contacts the rear concavity profile of the adjacent forward projectile at an annular contact area centered on the central axis.

[0136] Example 58 includes the ammunition round of Example 57, where when the round is fired, the tapered nose of the rearward projectile advances axially into the rear concavity profile of the adjacent forward projectile.

[0137] Example 59 includes the ammunition round of Example 57, where each of the two or more projectiles comprises a metal selected from copper, a copper alloy, gilding metal, brass, and steel.

[0138] Example 60 includes the ammunition round of any one of Examples 56-59, where each of the two or more projectiles comprise a core and a jacket.

[0139] Example 61 includes the ammunition round of Example 60, where the core comprises lead, lead alloy, tin, tin alloy, zinc, or a zinc alloy.

[0140] Example 62 includes the ammunition round of any one of Examples 60-61, where the jacket comprises copper, copper alloy, gilding metal, brass, or steel.

[0141] Example 63 includes the ammunition round of any one of Examples 56-62, where each of the two or more projectiles comprises a frangible material.

[0142] Example 64 includes the ammunition round of any one of Examples 56-63, where the tapered nose profile is ogival.

[0143] Example 65 includes the ammunition round of any one of Examples 56-63, where the tapered nose profile has a conical profile.

[0144] Example 66 includes the ammunition round of any one of Examples 64-65, where the tapered nose profile includes a mplat.

[0145] Example 67 includes the ammunition round of any one of Examples 56-66, where the rear concavity profile comprises a surface perpendicular to the central axis.

[0146] Example 68 includes the ammunition round of any one of Examples 56-67, where the nose profile of the rearward projectile differs from the rear concavity of the adjacent forward projectile in an angle defined with the central axis.

[0147] Example 69 includes the ammunition round of Example 68, where the angle differs from 1 to 20 degrees.

[0148] Example 70 includes the ammunition round of Example 68, where the angle differs from 2 to 15 degrees.

[0149] Example 71 includes the ammunition round of Example 68, where the angle differs from 4 to 10 degrees.

[0150] Example 72 includes the ammunition round of any one of Examples 56-71, where the two or more projectiles includes three projectiles.

[0151] Example 73 includes the ammunition round of any one of Examples 56-71, where the two or more projectiles includes four projectiles.

[0152] Example 74 is a multi-projectile ammunition cartridge comprising a straight-wall casing having an inside surface and extending along a central axis to a mouth with an inner diameter, and two or more coaxially aligned projectiles retained within a portion of the casing adjacent the mouth. Each projectile has a radially outer bearing surface in contact with the inside surface of the casing, a tapered nose with a nose profile, and a rear cavity with a cavity profile. The nose profile of a rearward projectile of the two or more projectiles differs from the cavity profile of an adjacent forward projectile of the two or more projectiles.

[0153] Example 75 includes the cartridge of Example 74, where the nose of the rearward projectile contacts the rear cavity of the adjacent forward projectile along an annular contact surface adjacent a rear end of the rear cavity, and where a portion of the nose that is forward of the contact surface is spaced axially and radially from the rear cavity.

[0154] Example 76 includes the cartridge of any one of Examples 74-75, where the inside surface includes a parallel portion adjacent the mouth and having an axial length of at least 1.5 times the inner diameter, the parallel portion being parallel to the central axis within an error of not more than 0.002 per inch of axial length.

[0155] Example 77 includes the cartridge of Example 76, where the error is not more than 0.0015 per inch of axial length.

[0156] Example 78 includes the cartridge of any one of Examples 76, where the error is not more than 0.001 per inch of axial length.

[0157] Example 79 includes the cartridge of any one of Examples 74-78, where each of the two or more projectiles comprises a metal selected from copper, a copper alloy, gilding metal, brass, or steel.

[0158] Example 80 includes the cartridge of any one of Examples 74-79, where each of the two or more projectiles comprises a core of a first material and a jacket of a second metal, the jacket at least partially covering the core.

[0159] Example 81 includes the cartridge of Example 80, where the first material comprises lead, lead alloy, tin, tin alloy, zinc, or a zinc alloy.

[0160] Example 82 includes the cartridge of any one of Examples 80 or 81, where the second material comprises copper, copper alloy, gilding metal, brass, or steel.

[0161] Example 83 includes the cartridge of any one of Examples 74-82, where each of the two or more projectiles comprises a frangible material.

[0162] Example 84 includes the cartridge of any one of Examples 74-83, where the nose profile is ogival.

[0163] Example 85 includes the cartridge of any one of Examples 74-83, where the nose profile is conical.

[0164] Example 86 includes the cartridge of any one of Examples 74-85, where the nose profile culminates in a mplat that is planar or concave.

[0165] Example 87 includes the cartridge of any one of Examples 74-86, where the cavity profile is ogival.

[0166] Example 88 includes the cartridge of any one of Examples 74-86, where the cavity profile is conical.

[0167] Example 89 includes the cartridge of any one of Examples 74-88, where the cavity profile comprises a surface perpendicular to the central axis.

[0168] Example 90 includes the cartridge of Example 89, where the nose of the rearward projectile of the two or more projectiles is wider than the rear cavity of the forward projectile due to an angle differential between the nose profile and the cavity profile, and where an angle of the nose profile is greater than an angle of the cavity profile with respect to the central axis.

[0169] Example 91 includes the cartridge of Example 90, where the angle differential is from 1 to 20 degrees.

[0170] Example 92 includes the cartridge of Example 90, where the angle differential is from 2 to 15 degrees.

[0171] Example 93 includes the cartridge of Example 90, where the angle differential is from 4 to 10 degrees.

[0172] Example 94 includes the cartridge of any one of Examples 74-93, where the nose of the rearward projectile contacts the rear cavity of the forward projectile at an annular contact area between the rear cavity and the nose, where the annular contact area is centered on the central axis.

[0173] Example 95 includes the cartridge of any one of Examples 74-94, where the cartridge defines a peripheral air space between the inside surface of the casing, the nose of the rearward projectile, and the rear cavity of the forward projectile.

[0174] Example 96 includes the cartridge of Example 95, where the peripheral air space is sealed.

[0175] Example 97 includes the cartridge of Example 96, where upon firing, the peripheral air space becomes sealed prior to the two or more projectiles leaving the casing.

[0176] Example 98 includes the cartridge of any one of Examples 74-97, where the two or more projectiles includes at least three projectiles.

[0177] Example 99 includes the cartridge of Example 98, where the two or more projectiles includes at least four projectiles.

[0178] Example 100 is a straight-wall cartridge casing having an outside surface, an inside surface. The casing extends along a central axis from a substantially closed first end defining a flash opening to an open mouth defining a groove diameter. A portion of the inside surface adjacent the mouth is parallel to the central axis within an error of not more than 0.002 per inch of length, and the portion having a length of at least 1.5 times the groove diameter.

[0179] Example 101 includes the casing of Example 100, where the error is not more than 0.0015 per inch of length.

[0180] Example 102 includes the casing of Example 100, where the error is not more than 0.001 per inch of length.

[0181] Example 103 includes the casing of any one of Examples 100-102, where the groove diameter is 0.510 inch.

[0182] Example 104 includes the casing of any one of Examples 100-102 and has a groove diameter for projectiles having a nominal diameter selected from 6.8 mm, 7.62 mm, 5.45 mm, and 0.50 inch.

[0183] Example 105 is a multi-projectile ammunition cartridge comprising a straight-wall casing having an inside surface and extending along a central axis to a mouth, and two or more projectiles coaxially aligned and retained in contact with the inside surface of the casing in a partially nested configuration.

[0184] Example 106 includes the multi-projectile ammunition of Example 105, where the nose profile is ogival.

[0185] Example 107 includes the multi-projectile ammunition of Example 105, where the nose profile is conical.

[0186] Example 108 includes the multi-projectile ammunition of any one of Examples 105-107, where the nose profile culminates in a mplat that is planar or concave.

[0187] Example 109 includes the multi-projectile ammunition of any one of Examples 105-108, where the cavity profile is ogival.

[0188] Example 110 includes the multi-projectile ammunition of any one of Examples 105-108, where the cavity profile is conical.

[0189] Example 111 includes the multi-projectile ammunition of any one of Examples 105-110, where the cavity profile comprises a surface perpendicular to the central axis.

[0190] Example 112 includes the multi-projectile ammunition of any one of Examples 105-111, where the nose of the rearward projectile of the two or more projectiles is wider than the rear cavity due to an angle differential between the nose profile and the cavity profile, and where an angle of the nose profile is greater than an angle of the cavity profile with respect to the central axis.

[0191] Example 113 includes the multi-projectile ammunition of Example 112, where the angle differential is from 1 to 20 degrees.

[0192] Example 114 includes the multi-projectile ammunition of Example 112, where the angle differential is from 2 to 15 degrees.

[0193] Example 115 includes the multi-projectile ammunition of Example 112, where the angle differential is from 4 to 10 degrees.

[0194] Example 116 includes the multi-projectile ammunition of Example 105, where a rearward projectile of the two or more projectiles has a nose with a nose profile and a forward projectile of the two or more projectiles has a rear cavity with a cavity profile, and where the nose of the rearward projectile contacts the rear cavity of the forward projectile along an annular contact surface adjacent a rear margin of the rear cavity, and where a portion of the nose forward of the contact area is spaced from the rear cavity.

[0195] Example 117 includes the multi-projectile ammunition of Example 116, where the nose includes a conical taper defining a first cone angle, and where the rear cavity includes a conical taper defining a second cone angle that is less than the first cone angle.

[0196] Example 118 includes the multi-projectile ammunition of Example 116, where the nose has a first ogival profile and the rear cavity has a second ogival profile, and where the first ogival profile has a greater radius of curvature than that of the second ogival profile.

[0197] Example 119 includes the multi-projectile ammunition of any one of Examples 105-118, where the inside surface includes a parallel portion adjacent the mouth, the parallel portion being parallel to the central axis within an error of not more than 0.002 per inch of length.

[0198] Example 120 includes the multi-projectile ammunition of Example 119, where the error is not more than 0.0015 per inch of length.

[0199] Example 121 includes the multi-projectile ammunition of Example 119, where the error is not more than 0.001 per inch of length.

[0200] Example 122 includes the multi-projectile ammunition of any one of Examples 105-121, where each of the two or more projectiles comprises a metal selected from copper, a copper alloy, gilding metal, brass, or steel.

[0201] Example 123 includes the multi-projectile ammunition of any one of Examples 105-121, where each of the two or more projectiles comprises a core of a first material and a jacket of a second metal, the jacket at least partially covering the core.

[0202] Example 124 includes the multi-projectile ammunition of Example 123, where the first material comprises lead, lead alloy, tin, tin alloy, zinc, or a zinc alloy.

[0203] Example 125 includes the multi-projectile ammunition of any one of Examples 123 or 124, where the second material comprises copper, copper alloy, gilding metal, brass, or steel.

[0204] Example 126 includes the multi-projectile ammunition of any one of Examples 105-125, where each of the two or more projectiles comprises a frangible material.

[0205] Example 127 includes the multi-projectile ammunition of any one of Examples 105-126, where the cartridge defines a peripheral air space between the inside surface of the casing, the nose of the rearward projectile, and the rear cavity of the forward projectile.

[0206] Example 128 includes the multi-projectile ammunition of Example 127, where the peripheral air space is sealed.

[0207] Example 129 includes the multi-projectile ammunition of Example 127, where upon firing, the peripheral air space becomes sealed prior to the two or more projectiles leaving the casing.

[0208] Example 130 includes the multi-projectile ammunition of any one of Examples 105-129, where the two or more projectiles includes at least three projectiles.

[0209] Example 131 includes the multi-projectile ammunition of any one of Examples 105-129, where the two or more projectiles includes at least four projectiles.

[0210] Example 132 is a method of manufacturing a cartridge case, the method comprising forming a metallic cylinder that extends along a central axis from a closed end with a primer pocket to an open end; defining an extractor groove in the cylinder adjacent the closed end; defining a flash opening in the primer pocket, the flash opening aligned with the central axis; forming an exterior taper on an outer surface of the cartridge case; and shaping part of the inside surface of the cylinder adjacent the open end to be parallel to the central axis within an error of not more than 0.002 per inch of length, the part of the inside surface that is parallel having an axial length of at least 1.5 times an interior diameter of the open end.

[0211] Example 133 includes the method of Example 132 and further comprises disposing a primer within the primer pocket.

[0212] Example 134 includes the method of any one of Examples 132-133 and further comprises disposing propellant within the cylinder.

[0213] Example 135 includes the method of any one of Examples 132-134 and further comprises disposing two or more axially aligned projectiles within the cylinder and engaged by the inside surface that is parallel to the central axis.

[0214] Example 136 includes the method of Example 135, where disposing the two or more axially aligned projectiles includes disposing at least three axially aligned projectiles within the cylinder and engaged by the inside surface that is parallel to the central axis.

[0215] Example 137 includes the method of Example 135, where disposing the two or more axially aligned projectiles includes disposing at least four axially aligned projectiles within the cylinder and engaged by the inside surface that is parallel to the central axis.

[0216] Example 138 includes the method of any one of Examples 132-137, where the error is not more than 0.001 per inch of length.

[0217] Example 139 includes the method of any one of Examples 132-138, where the axial length is at least 1.5 times the interior diameter of the open end.

[0218] The foregoing description of examples and aspects thereof has been presented for the purposes of illustration and description. It is not intended to be exhaustive or the limit the present disclosure to the precise forms disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto. Future-filed applications claiming priority to this application may claim the disclosed subject matter in a different manner and generally may include any set of one or more limitations as variously disclosed or otherwise demonstrated herein.