Small caliber ammunition cartridge and armor piercing match bullet thereof

Abstract

A small-caliber projectile having a length Lb, a forward ogive-shaped section, a rear generally cylindrical shaped section, a core, and a jacket generally surrounding the core. The core has a front/penetrator core portion and a soft/heavy rear core portion, wherein the front/penetrator core portion is made of a tungsten alloy and has a length Lp and the soft/heavy rear core portion is made of a lead alloy and has a length Lr and the ratio Lp to Lb is in the range of 0.2 to 0.5.

Claims

1. A small-caliber projectile having a length Lb, the projectile comprising: a forward ogive-shaped section; a rear generally cylindrical shaped section; a core; and a jacket generally surrounding the core; wherein the core includes a front/penetrator core portion and a soft and heavy rear core portion, the front/penetrator core portion being made of a tungsten alloy and having a length Lp and the sof and heavy rear core portion being made of a lead alloy and having a length Lr and wherein the ratio Lp to Lb is in the range of 0.2 to 0.5.

2. The projectile of claim 1, wherein the ratio Lp to Lb is in the range of 0.3 to 0.4.

3. The projectile of claim 1, wherein the front/penetrator core portion and the soft and heavy rear core portion have a flat interface there-between.

4. The projectile of claim 3, wherein the interface is transverse to the projectile.

5. The projectile of claim 1, wherein the front/penetrator core portion has a concave rear end; and the soft and heavy rear core portion has a corresponding convex front end.

6. The projectile of claim 1, wherein the front/penetrator core portion comprises a front shape angle between 90 and 130 degrees.

7. The projectile of claim 1, wherein the front/penetrator core portion has a diameter dp at its largest width and the projectile has a diameter Db at its largest width, and the ratio of dp to Db is between 0.75 and 0.82.

8. The projectile of claim 1, wherein the mass of the front/penetrator core portion with respect to the mass of the projectile is between 0.2 and 0.3.

9. The projectile of claim 1, wherein the mass of the soft and heavy rear core portion with respect to the mass of the projectile is between 0.4 and 0.6.

10. The projectile of claim 1, wherein the projectile has a length in the range of 22.5 mm to 25 mm.

11. The projectile of claim 1, wherein the projectile has a weight range of 4.2 g to 5.2 g.

12. The projectile of claim 1, wherein the front/penetrator core portion is made of a tungsten-carbide (WC) alloy having a range of 85% to 95% WC.

13. The projectile of claim 1, wherein the front/penetrator core portion has a density in the range of 14.20 to 14.80 g/cc.

14. The projectile of claim 1, wherein the front/penetrator core portion has a Vickers Hardness HV(30) greater than 1, 570.

15. The projectile of claim 1, wherein the front/penetrator core portion has a transverse rupture strength (TRS) greater than 2,500 MPa.

16. The projectile of claim 1, wherein the front/penetrator core portion has a grain size less than 1 μm.

17. The projectile of claim 1, wherein the rear generally cylindrical shaped section has a tapered/boat tail rear end portion.

Description

DRAWINGS

(1) The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

(2) FIG. 1 is a cross-sectional view of an ammunition round of the present invention in accordance with embodiments thereof.

(3) FIG. 2 is a cross-sectional view of a projectile portion (bullet) of the ammunition round of the present invention in accordance with embodiments thereof.

(4) FIG. 3 is a cross-sectional view of FIG. 2 in greater detail.

(5) FIG. 4 is a cross-sectional view of similar to FIG. 2 illustrating an exemplary embodiment.

(6) FIG. 5 is a series of graphs indicating test results regarding design factors of the present bullet.

(7) FIG. 6 is a graph integrating the test results of the graphs in FIG. 4.

(8) FIG. 7 is a bar graph comparing the accuracy, by way of spread radius, of the present bullet to two prior art bullets.

(9) FIG. 8 is a graph showing trajectory matching of the present bullet to prior art bullets at two firing angles.

(10) FIG. 9 is a graph showing trajectory matching of the present bullet to a same caliber bullet at a shorter range than FIG. 7.

(11) FIG. 10 is a table showing an exemplary penetration comparison of the present bullet to prior art bullets.

(12) Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

(13) Example embodiments will now be described more fully with reference to the accompanying drawings.

(14) Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

(15) The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

(16) When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

(17) Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

(18) Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

(19) FIG. 1 shows an ammunition round 100 of the present invention in accordance with embodiments thereof. Ammunition round 100 includes gun powder 10; a casing 20; a primer 30; a projectile or bullet 40; and sealant 50.

(20) As the invention relates in particular to the projectile or bullet 40 of round 100, further details of the above mentioned components will not be described in further detail.

(21) FIGS. 2 and 3 show embodiments of projectile/bullet 40 of ammunition round 100, FIG. 3 being a more detailed depiction of FIG. 2. Bullet 40 has a length Lb and includes an ogive-shaped front section; and a cylindrical rear section having a tapered/boat-tail rear end portion.

(22) In some embodiments, (with reference to FIG. 3) the overall length of the bullet (Lb) is 22.5 mm to 25 mm; the weight is 4.2 g to 5.2 g; and the ogive portion has the following specifications: 0.5≤(Lo+Lβ)/Lb≤0.55; and the boat tail portion has the following specifications: 0.1≤Lγ/Lb≤0.12.

(23) In some embodiments, the front (hard/penetrator) core portion is made of a tungsten-carbide (WC) alloy having a range of 85% to 95% WC. In some embodiments, the front (hard/penetrator) core portion has the following specifications: density of 14.20 to 14.80 g/cc; Vickers Hardness HV(30)≥1, 570; transverse rupture strength (TRS)≥2,500 MPa; grain size<1 μm.

(24) In some embodiments (with reference to FIG. 3) the penetrator portion has the following geometry: its cylindrical ring portion (gp1) has a length≤0.3 mm; an external shape radius; an angle point alpha (α) between 90 and 130 degrees; a flat ring surface (gp2) between 0.03 and 0.1 mm disposed between the angle point and the radius shape. The ratio of the large diameter (dp) of the penetrator core to the bullet diameter (Db) is:

(25) $0.75\le \frac{d_p}{D_b}\le 0.82$

(26) In some embodiments the weight of the penetrator portion with respect to the bullet is

(27) $0.20\le \frac{Mas{s}_{\mathrm{penetrator}}}{Mas{s}_{\mathrm{projectile}}}\le 0.30$

(28) In some embodiments, the (soft and heavy) rear core portion is made of a MIL-L-13283 Grade 1 lead alloy; and has the following weight ratio range of core to projectile:

(29) $0.4\le \frac{Mas{s}_{\mathrm{rear}\mathrm{core}}}{Mas{s}_{\mathrm{projectile}}}\le 0.6$

(30) Bullet 40 includes a jacket 42, commonly made of brass or coated steel; and a core 60 with a front core portion 62 (also known as a penetrator) having a length Lp; and a rear core portion 64 having a length Lr. Jacket 42 has a bearing surface that is the widest portion of bullet 40 and which interfaces with the gun barrel (not shown) during firing.

(31) Front core portion 62 is made of a wolfram/tungsten (W) alloy, which is a hard/penetrator portion; and rear core portion 64 is made of a lead (Pb) alloy, which is a soft and heavy/dense portion. There is a front-core/rear-core interface 66 between front core portion 62 and rear core portion 64 that is generally flat and transversely oriented. The flat interface 66 is advantageous in both manufacturing and regarding penetration, as the softer lead-alloy rear core portion 64 (which is dense/heavy due to the lead content, as noted) will tend to press on the hard/penetrator front core portion 62 upon impact of bullet 40 with its target (e.g. armor), thus preserving the overall and impact kinetic energy to the extent possible.

(32) It is a particular feature of bullet 40 that there is a ratio Lp/Lb between the length Lp of the penetrator (front core portion 62) and the length Lb of the bullet that provides a preferable design (preferred trade-off in terms of the resultant combination of design factors, in particular: cost, accuracy, gun barrel wear, and penetration—while preferably also providing a close trajectory match to the standard 5.56 mm bullet (or other caliber, mutatis mutandis).

(33) FIG. 4 shows an alternate embodiment wherein the interface 66 is provided by front core portion 62 having a concave rear end 63, and rear core portion 64 having a corresponding convex front end 65. This design can save on material costs of the more expensive front/penetrator core portion 62; and, without limitation to theory, this design can also help the kinetic energy transfer from the dense rear core portion 64 to the front/penetrator core portion 62.

(34) FIG. 5 shows a series of graphs indicating test results regarding design factors of the present bullet including accuracy (dispersion/spread); barrel erosion; penetration; and cost (price) of producing the bullet. It should be noted and obvious that each one of these parameters is extremely important and also not easily balanced, i.e. there can be difficult trade-offs.

(35) As can be seen, also with reference to FIG. 6, that the accuracy improves with a balance of front to rear core lengths whereby the penetrator length Lp (length of front core 62) to the overall bullet length, Lb, i.e. Lp to Lb ratio, is in the general range of 0.3 to 0.5.

(36) Regarding barrel erosion, it can be seen that a low penetrator length Lp (length of front core 62) to overall bullet length, Lb, is preferable, in the Lp to Lb ratio range of 0 to 0.4.

(37) Regarding penetration, it can be seen that a fairly balanced ratio of penetrator length Lp (length of front core 62) to overall bullet length, Lb, is preferable, in the Lp to Lb ratio range of 0.4 to 0.5. However, as will be discussed below, bullet penetration with a design having a Lp/Lb ratio range of 0.3 to 0.4 provides sufficient penetration.

(38) Regarding price/cost, it is not surprising to see that a low penetrator length Lp (length of front core 62) to overall bullet length, Lb, is preferable, as the material of front/penetrator core portion 62 is expensive. However, it is believed that the cost is reasonable in the Lp/Lb ratio range of 0.3 to 0.4, in particular in light of the fact that if the accuracy and penetration parameters are not adequate, no amount of cost savings is sufficient.

(39) As described below, a bullet was tested, which had the following specifications: Lp/Lb=0.35; bullet diameter of 5.56 caliber; jacket material: brass 90/10; the rear core portion was a MIL-L-13283 Grade 1 lead alloy; and a penetrator core tungsten-carbide alloy with a density of 14.45 g/cc.

(40) FIG. 7 is a bar graph comparing the accuracy, by way of spread radius, of the present bullet (termed 5.56 mm APM—Armor Piercing Match) to two prior art bullets, namely the 7.62 mm caliber M80 and the 5.56 mm caliber M855. As can be seen, the present bullet (5.56 mm APM) has superior accuracy at the 550 meter range with a mean spread/dispersion radius of about 10 cm, compared to about 13 cm for the 7.62 mm M80 and about 15.5 cm for the 5.56 mm caliber M855.

(41) FIGS. 8 and 9 illustrate the excellent trajectory matching of the present bullet to prior art bullets. FIG. 8 shows that the present (5.56 APM) bullet has excellent trajectory matching, especially at low to medium range, at a 2-degree firing angle, compared to the 7.62 mm caliber M80 and 5.56 mm caliber M855 bullets. In a comparison at a 1-degree firing angle, the present (5.56 mm APM) bullet also showed excellent trajectory matching, especially at low to medium range, compared to the 5.56 mm caliber M855 bullet.

(42) FIG. 9 shows the excellent trajectory matching of the present bullet to the same caliber bullet (5.56 mm M855) at an effective firing range.

(43) FIG. 10 compares the penetration between the present bullet to that of the 7.62 mm caliber M80 and 5.56 mm caliber M855 bullets. As noted, the present (5.56 mm APM) bullet achieves a 100% penetration through a 7 mm thick armored plate (i.a.w., MIL-A-12560H) at a range of 100 meters and a range of 200 meters, whereas the neither of the 7.62 mm caliber M80 and 5.56 mm caliber M855 bullets penetrate at either test range.

(44) The table of FIG. 10 shows other penetration tests results wherein the present (5.56 mm APM) bullet achieves a 100% penetration through a 3.4 mm thick standard NATO steel plate constituted in one test by two plates and tested at a 570 meter range; and one plate at an 800 meter range. In contrast, neither the 7.62 mm caliber M80 bullet nor the 5.56 mm caliber M855 bullet penetrates at the 570 meter range; and the 7.62 mm caliber M80 bullet did not penetrate at the 800 meter range. Other test results presents 5.56 mm APM bullet achieves a 100% penetration through a 7 mm thick armored plate MIL-A-12560H at ranges of 100 and 200 meters. In contrast, neither the 7.62 mm caliber M80 bullet nor the 5.56 mm caliber M855 bullet penetrates the 7 mm armored plate.

(45) With reference to the results shown in the table below, calculation of a fire-power coefficient will now be addressed.

(46) Table comparing operation of the present APM bullet to NATO-standard bullets (with reference to FIG. 7 to FIG. 10):

(47) TABLE-US-00001 Accuracy Penetration Weight Bullet type improvement improvement reduction 5.56 mm Ball 35% 100%  −5% 7.62 mm Ball 30% 100% 100%

(48) The principle parameters determining fire power of infantry troops are: accuracy; penetration; and weight of the weaponry. Using a weighting of 0.4 for accuracy; 0.4 for penetration; and 0.2 for weaponry weight, fire power can be calculated as:
Fire Power=Accuracy+Penetration+Weight=0.4A+0.4P+0.2W
F.P.(APM vs. M855)=0.4*1.35+0.4*2+0.2*0.95=1.53
F.P.(APM vs. M80)=0.4*1.30+0.4*2+0.2*2=1.72

(49) The results of the calculations indicate that the effectiveness of the present bullet tested is about 50% better than the M855/SS109; and at least 70% better than the M80. And, with consideration of the resultant weight savings of the weapon and bullet, the improvement in effectiveness of the present bullet can reach about 90% compared to the M80.

(50) Considering the above parameters and calculations, the present bullet is an excellent choice to replace the above-mention BALL projectiles for infantry troops. Such a replacement will result in improved fire-power, penetration, weight reduction, and lower cost, while retaining the present 5.56 mm caliber parameter, thus avoiding rifle replacement and potentially reducing/eliminating the need for other caliber bullets and associated weaponry.

(51) The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.