BOLT CARRIER WITH GAS EXHAUST POCKET

Abstract

A bolt carrier for gas impingement rifles equipped with a sound suppressor mechanism. The bolt carrier is configured to tortuously direct gas to a gas exhaust pocket and into a magazine well of the gas impingement rifle, thereby lessening ejection port light signature and significantly reducing the peak noise in the vicinity of the firer's ears. The gas exhaust pocket of the bolt carrier also improves the operator air quality and reduces bolt lug and chamber fouling associated with the other devices that have attempted to address the noise problem.

Claims

1. A bolt carrier group for a breechloading firearm, wherein the bolt carrier group is capable of operative association with a housing or a receiver that is provided with a cartridge case ejection port, the bolt carrier group comprising: a bolt carrier having a first side and a second side defined and separated by a housing centerline of the housing or the receiver operatively associated with the bolt carrier group, wherein the first side is adjacent said cartridge case ejection port; a gas exhaust pocket disposed in the second side; one or more exhaust ports fluidly communicating the gas exhaust pocket with an internal exhaust-pressurized portion of the bolt carrier; and the gas exhaust pocket defined in part by snug operative association with the housing or the receiver so that exhaust gas received into the gas exhaust pocket from the internal exhaust-pressurized portion of the carrier via the one or more exhaust ports expands in the pocket.

2. The bolt carrier group of claim 1, wherein a portion of the gas exhaust pocket comprises an aperture.

3. The bolt carrier group of claim 2, wherein the aperture directs the received exhaust gas into a forward portion of an ammunition feed magazine of the breechloading firearm.

4. The bolt carrier group of claim 2, wherein the gas exhaust pocket comprises a forward sealing surface dimensioned and shaped to direct the received exhaust gas via an aperture along a tortuous path to an external environment.

5. The bolt carrier group of claim 4, wherein the aperture is geometry manufactured into the second side of the housing or the receiver.

6. The bolt carrier group of claim 2, wherein there are no gas exhaust ports along an exterior of the first side of the bolt carrier.

7. A method of simultaneously reducing an ejection port light signature and reducing a decibel level of a peak operating noise level of a breechloading firearm, the method comprising: diverting exhaust gas received by a bolt carrier optatively associated with the breechloading firearm, via ejection ports, to a gas exhaust pocket formed along an exhaust side of the bolt carrier opposite an ejection side of the bolt carrier, wherein the ejection side is adjacent a cartridge case ejection port of a receiver or a housing of the breechloading firearm.

8. The method of claim 7, further comprising directing the exhaust gas through an aperture of the gas exhaust pocket, wherein the aperture is along a forward portion of the gas exhaust pocket, so that the exhaust gas urged into a forward portion of an ammunition feed magazine of the breechloading firearm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a non-ejection port side elevation view of an exemplary embodiment of an assembled bolt carrier 1 of the present invention, shown operatively associated with a bolt 10. The non-ejection port side being the side of the bolt carrier that faces the majority right-handed user during typical stronghanded firing of the firearm, and the side where the gas pocket 20 is disposed.

[0026] FIG. 2 is a non-ejection port side elevation view of an exemplary embodiment of the bolt carrier 1 of the present invention, shown without the bolt 10.

[0027] FIG. 3 is an ejection port side elevation view of an exemplary embodiment of the bolt carrier 1 of the present invention, showing the absence of prior art gas ports in the ejection port side of the bolt carrier 1.

[0028] FIG. 4 is a top rear, non-ejection port side perspective view of an exemplary embodiment of the present invention.

[0029] FIG. 5 is a rifle cutaway view from the muzzle side perspective looking toward the rear of the rifle. This drawing is of an approximate 0.06 increased bolt unlocking stroke, illustrating the cam-pin path version of the exemplary embodiment of the invention, showing the orientation of components at a location where the gas rings have passed the gas pocket exhaust ports by approximately 0.093. This view shows the forward part of the magazine and cartridges, for contextual understanding of the relatively open volume of that area of the magazine.

[0030] FIG. 6 is a gas pocket side perspective cutaway view of the rifle, affording contextual understanding of the gas pocket aperture position of the rifle at the same stroke position as in FIG. 5. This view is intended to show the aperture over the forward, open portion of the rifles ammunition feed magazine. It is worth noting that a standard cam-pin path bolt carrier version of the invention exists for compatibility of standard market bolts, which would put this identical carrier exhaust position 0.06 further forward than shown in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

[0032] Broadly, an embodiment of the present invention provides a bolt carrier for gas impingement rifles equipped with a sound suppressor mechanism. The bolt carrier is configured to direct gas to a gas exhaust pocket, thereby lessening ejection port light signature and significantly reducing the peak noise in the vicinity of the firer's ears. The bolt carrier with a gas exhaust pocket further improves the operator air quality and reduces bolt lug and chamber fouling associated with the prior art devices that have attempted to address the noise problem.

[0033] Referring to FIGS. 1, 5, and 6, the present invention may include a bolt carrier 1 providing a gas pocket 20 along the non-ejection port side of the bolt carrier 1. The bolt carrier 1 has one or more exhaust slots 21 fluidly coupled to the gas pocket 20 provided with the body of the bolt carrier 1.

[0034] The gas pocket 20 may communicate with an aperture 24 in the non-ejection port side of bolt carrier 1. The shape and dimensions of the gas pocket 20 are such that when the bolt carrier 1 is moving rearward-under the urging of the expanding gases of ignited propellant that is channeled into the bolt carrier key 28 via the gas tube 29the gas rings 36 of the bolt 10 pass the one or more exhaust ports or slots 21, allowing the said expanding exhaust gases to fill the gas pocket 20. The aperture 24 in the gas pocket 20 allows the expanded exhaust gas to be directed downward into the relatively open forward portion of the rifle's ammunition feed magazine 30, which in FIGS. 5 and 6 is located by a magazine well in lower receiver 32. After the exhaust gas expands into the magazine well it can escape the gaps in the magazine floorplate or through the opening ejection port 33 of the housing or receiver (not to be confused with the prior art bolt-carrier gas exhaust ports along the side of the bolt carrier adjacent the ejection port).

[0035] Forward sealing surface 25 of the exhaust gas pocket 20 provides an obstacle between exhaust gas and the bolt and chamber of the firearm. Forward wall or sealing surface 25 of gas pocket 20 can also act as a carbon scraper when the bolt carrier 1 cycles, keeping the inside walls of the upper receiver, or the like that the bolt carrier 1 is operably associated with, clean for operation. The sealing surface 25 stops gas from being able to push forward into the bolt lug/chamber area in a direct path. The gas pocket 20 pressurizes and the expanded lower pressure gas vents downward through the aperture 24 into the forward portion of the magazine well which is occupied only by a staggered double column of 0.224 diameter bullets 38 in a 0.794 inside width magazine (in the case of a 5.56 mm rifle), so there is plenty of open space up front (45% open space before considering the pointed shape of the bullet) for the gas to vent along path 37 into and expand in the magazine, before either leaving gaps at the magazine floorplate, or the opening ejection port of the housing or receiver as the bolt carrier travels rearward as shown in FIG. 6. In FIG. 6. the longer stroke and therefore 0.06 more rearward bolt carrier is shown at the moment of unlocking with the cam pin 34 at the forwardmost location in the cam pin track 39, and the gas rings 36 have passed the rear of the exhaust ports 21 by approximately 0.093 in this position, demonstrating the aperture 24 is capable of venting exhaust gas along the aforementioned path 37 into the forward open portion of the magazine well for expansion and cooling prior to exiting the ejection port 33.

[0036] Note that notch 27 in FIG. 3 is not related to the scope of the invention and is a safety feature in the event of a case head failure, intended to permit gas to exit the ejection port safely without splitting the bolt carrier 1 at the magazine feed lip clearance slots on the bottom of the bolt carrier, as is typical in prior art bolt carriers during catastrophic failure of a cartridge case from unsafe, over loaded and over pressure rounds.

[0037] As shown in FIGS. 1, 2, and 3 the present invention may pertain to the addition of a gas exhaust pocket 20 to an AR-15 bolt carrier 1. When the prior art rifle is fired, gas flows through a port in the barrel of the rifle, into a gas tube 29, and through the bolt carrier key 28 on the bolt carrier 1. The gas enters a chamber in the bolt carrier 1 behind the gas rings of the bolt 10 and forces the bolt carrier 1 rearward independent of the bolt which is at this point engaged with lugs locked in battery inside the barrel extension. When the slot or plurality of slots 21 passes the gas rings 36 on the bolt, the gas is exhausted angularly forward into the gas pocket 20, and after initially expanding there, is directed downward and forward through the aperture 24.

[0038] The gas exhausted from slot or slots 21 is expelled into the gas pocket 20 on the non-ejection port side of bolt carrier 1 and is functionally restricted or bounded in assembly by the firearms upper receiver which is closely associated with the bolt carrier 1 during the firing cycle by a close diameter to diameter, sliding fit. The gas that has expanded into pocket 20, is directed downward, in part by reflecting off the sealing surface 25 through the notch or aperture 24 into the open forward portion of the rifle's magazine, allowing it to expand and diminish in pressure.

[0039] The gas that has passed through aperture 24 and expanded into the open forward portion of the rifle's magazine, is now able to exit the opening ejection port in the upper receiver as bolt carrier 1 has opened sufficiently and rapidly, to permit the gas to escape.

[0040] During the firing cycle, the forward sealing surface 25 of the gas pocket 20 in the bolt carrier 1 can shield the chamber from directly injected fouling, and act as a carbon scraper, keeping the sidewall of the upper receiver clean, and depositing any debris into the liberal tolerance, open forward portion and sidewall of the magazine of the rifle. The provision of allowance for the expansion and cooling of exhaust gas prior to escaping the rifle, allows the peak sound in the vicinity of the firer's ears to drop approximately 9 decibels. This effect is only measurable when the rifle is fired with a high-performance, barrel muzzle attached silencer. When the silencer is not present, the muzzle signature overwhelms the peak sound from the bolt carrier port exhaust, by virtue of being the louder of the two sounds present. So, this invention only increases the hearing safety of the AR-15, when a typical barrel end attached sound suppressor is already installed on the muzzle of the barrel. The bolt carrier of the invention, when tested, increased the right ear's safe exposure limit 250% according to the Army Research Laboratory, Auditory Hazard Assessment Algorithm for Humans (AHAAH) software tool, and Bruel & Kjaer Pulse sound metrology system. The measurement tools and dosing software used are currently state of the art. An approximately 9 decibels drop in shooter right ear sound is an incredible amount of safety gain over currently state of the art silencers used in conjunction with a standard bolt carrier group. At the present time, the military is pursuing low cyclic increase sound suppressors, and in order to be low cyclic increase, the state of the art in these silencers have unsafe unweighted and A weighted ear sound signature that 9 DB drop would often put into an ear safe profile, allowing the military to make both ear and respiratory hazards safe, rather than compromising hearing safety for respiratory safety.

[0041] Gas pocket 20 in bolt carrier 1 allows controlled environment expansion of gas exhausted from slot or plurality of slots 21. The open portion of the firearms magazine 30 provides a second controlled environment for expansion prior to exhaust gas reaching the open ejection port 33 where it can only then create an impulse noise signature. The expansion areas reduce the capability of the exhaust gas to create high impulse sound levels.

[0042] Manufacturing a bolt carrier with the features detailed in this document and using it in a direct impingement rifle such as an AR-15 with a muzzle attached sound suppressor will provide the additional reduction of operator ear sound previously mentioned in this application. The features could also be added to a bolt carrier with or without the ports on the ejection port side deleted, however the deletion of the ports on the ejection port side will promote the lowest ear sound levels.

[0043] Manufacturing the aperture or opening of the gas exhaust pocket into the housing or receiver that completes the operative association of the two components would be a mechanical re-arrangement that would provide similar function to the invention. This would rely on bolt carrier stroke timing and would become open and then again closed at two points in the carrier stroke, which may delete or improve a portion of functionality.

[0044] The gas pocket can be deleted, but this will have an adverse effect on the toxic gas in the vicinity of the firer's face. Deleting the pocket will permit greater pressurization of the firearms receiver to occur, allowing gas to be exhausted from the vicinity of the charging handle and the upper to lower receiver's thin communicative mating surface gap, as well as the trigger's hole in the fire control pocket. This gas is not breathable clean air, so it should be mitigated as well as possible with the gas pocket 20 and fluidly coupled aperture 24.

[0045] The slots could be ports; however, slots would better direct the gas exhaust distally away from the firer's face, toward the purposeful aperture 24, thereby improving air quality in the vicinity of the firer's face and better reducing localized pressure and debris associated wear on parts. The slots angular flow promotes a glancing, distal and diagonal flow of gas, reducing impact wear to the rifle's upper receiver. In testing, during the firing of thousands of rounds at a high rate of fire, the wear to the upper receiver caused by these features was not measurable or visible and did not wear or break through the hard coat anodizing.

[0046] Toxic gas is a major concern for auto-loading rifles. The ports in the ejection port side of the carrier were deleted, however they could be left behind, and there would still be less sound, because the pressure would be dropped by opening other ports, and the exhaust ports and or slots on the non-ejection port side of the carrier could be slightly proximally located relative to the ejection port side ports or slots, and that would be a mechanism to drop pressure before the ejection port side noise occurred, because proximal port locations are associated with earlier exhaust gas release during the firing sequence.

[0047] A method of using the present invention may include the following. A user may attach a silencer to the direct impingement firearm. This firearm could be an Ar-15 or AR-10 or another similar firearm. Replace the bolt carrier group with a bolt carrier group with the bolt carrier embodied in the present invention. When firing the firearm, the operator ear peak sound levels will have dropped approximately 9 decibels, and the dosing safety limit will have increased approximately 250% as indicated by our testing of this system. Further, the ejection port flash signature will have been eliminated.

[0048] As used in this application, the term about or approximately refers to a range of values within plus or minus 10% of the specified number. And the term substantially refers to up to 80% or more of an entirety. Recitation of ranges of values herein are not intended to be limiting, referring instead individually to any and all values falling within the range, unless otherwise indicated, and each separate value within such a range is incorporated into the specification as if it were individually recited herein.

[0049] For purposes of this disclosure, the term aligned means parallel, substantially parallel, or forming an angle of less than 35.0 degrees. For purposes of this disclosure, the term transverse means perpendicular, substantially perpendicular, or forming an angle between 55.0 and 125.0 degrees. Also, for purposes of this disclosure, the term length means the longest dimension of an object. Also, for purposes of this disclosure, the term width means the dimension of an object from side to side. For the purposes of this disclosure, the term above generally means superjacent, substantially superjacent, or higher than another object although not directly overlying the object. Further, for purposes of this disclosure, the term mechanical communication generally refers to components being in direct physical contact with each other or being in indirect physical contact with each other where movement of one component affect the position of the other.

[0050] The use of any and all examples, or exemplary language (e.g., such as, or the like) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the embodiments or the claims. No language in the specification should be construed as indicating any unclaimed element as essential to the practice of the disclosed embodiments.

[0051] In the following description, it is understood that terms such as first, second, top, bottom, up, down, and the like, are words of convenience and are not to be construed as limiting terms unless specifically stated to the contrary.

[0052] It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.