BOLT CARRIER FOR SEMI-AUTOMATIC and AUTOMATIC FIREARM

Abstract

A firearm magazine and a corresponding bolt carrier assembly are provided herein. The firearm magazine includes a magazine body, with the magazine body having a width to accommodate a double stack of cartridges in a zigzag pattern. The firearm magazine also includes a spring coupled to a follower within the magazine body. The magazine body also includes two feed lips coupled to the magazine body, where the two feed lips together hold a single cartridge in place in a center of the magazine body to allow a bolt carrier to push the single cartridge out of the firearm magazine and into a chamber of a firearm. The bolt carrier includes feed lip channels configured to accommodate the feed lips therein. A cocking surface is located between the feed lip channels and has a width of less than 0.400 inches.

Claims

1. A bolt carrier assembly, comprising: a body having an elongated cylindrical shape with a first end opposite a second end, the body having a central axis extending from the first end to the second end; two feed lip grooves formed in a surface of the body adjacent to the first end, the feed lip grooves extend parallel to one another from the first end toward the second end; and a cocking surface between the feed lip grooves, the cocking surface having a width of about 0.200 inches to about 0.380 inches.

2. The bolt carrier assembly of claim 1, wherein the cocking surface is parallel to the feed lip grooves.

3. The bolt carrier assembly of claim 1, wherein the body further comprises a stepped surface formed in the body.

4. The bolt carrier assembly of claim 3, wherein the stepped surface is opposite and parallel to the cocking surface.

5. The bolt carrier assembly of claim 1, wherein a width of the cocking surface is about 28% to about 38% of a width of the body.

6. The bolt carrier assembly of claim 1, wherein the body further comprises a tapered portion adjacent to the cocking surface and the cocking surface is between the tapered portion and the first end of the body.

7. The bolt carrier assembly of claim 6, wherein the cocking surface extends between the first end and the tapered portion.

8. A bolt carrier assembly, comprising: a body having a first end opposite a second end, the body having a central axis extending therethrough, the central axis extending from the first end to the second end; and a cocking surface formed in the body adjacent to the first end, a width of the cocking surface corresponding to a cartridge diameter, the width of the cocking surface less than 0.400 inches, the body configured to accommodate a double stack, single feed magazine.

9. The bolt carrier assembly of claim 8, wherein the width of the cocking surface is about 28% to about 38% of a width of the body.

10. The bolt carrier assembly of claim 8, wherein the width of the cocking surface is about 0.200 inches to about 0.380 inches.

11. The bolt carrier assembly of claim 8, further comprising a stepped surface formed in the body opposite the feed lip grooves.

12. The bolt carrier assembly of claim 11, wherein the stepped surface is opposite and parallel to the cocking surface.

13. The bolt carrier assembly of claim 12, wherein the body further comprises a tapered portion adjacent to the cocking surface and opposite the first end of the body.

14. The bolt carrier assembly of claim 13, wherein the cocking surface extends between the first end and the tapered portion.

15. The bolt carrier assembly of claim 13, wherein the body further comprises two feed lip grooves formed in the body adjacent to the first end, the feed lip grooves are parallel to one another opposite the stepped surface, and the feed lip grooves extend from the first end to the tapered portion.

16. A firearm assembly, comprising: a barrel having a barrel extension; a plurality of bolt lug recesses formed in the barrel extension; a double stack single feed magazine having two feed lips, wherein a bolt channel is formed between the two feed lips; and a bolt carrier assembly comprising: a body having a first end and a second end, the body having a central axis extending from the first end to the second end; one or more feed lip grooves formed in the body, the feed lip grooves configured to accommodate the feed lips therein; a cocking surface formed in the body between the feed lip grooves, the cocking surface substantially parallel to the one or more feed lip grooves, the cocking surface having a width of about 0.200 inches to about 0.380 inches; and a bolt disposed in the first end of the body.

17. The firearm assembly of claim 16, wherein the bolt comprises a plurality of bolt lugs, each bolt lug of the plurality of bolt lugs corresponding to at least one bolt lug recess of the plurality of bolt lug recesses which correspond to the plurality of bolt lug recesses.

18. The firearm assembly of claim 16, wherein a width of the bolt channel is about 80% to about 90% of a diameter of a cartridge in the double stack single feed magazine.

19. The firearm assembly of claim 16, wherein the cocking surface of the body is configured to be positioned between the feed lips of the double stack single feed magazine.

20. The firearm assembly of claim 16, wherein the bolt comprises a tapered portion and the cocking surface extends between the first end and the tapered portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0042] FIG. 1A illustrates a rear view of a loaded double stack/double feed configured magazine.

[0043] FIG. 1B illustrates a rear view of a loaded single stack/single feed configured magazine.

[0044] FIG. 2 illustrates a top view of a loaded double stack/double feed configured magazine.

[0045] FIG. 3 illustrates a rear view of an unloaded double stack/double feed configured magazine.

[0046] FIG. 4 illustrates top, side, and rear views of a double stack/double feed magazine, curved with stiffening grooves.

[0047] FIG. 5 illustrates top, side, and rear views of a double stack/double feed magazine, straight with stiffening grooves.

[0048] FIG. 6 illustrates top, side, and rear views of a double stack/double feed magazine, curved without stiffening grooves.

[0049] FIG. 7 illustrates top, side, and rear views of a double stack/double feed magazine, straight without stiffening grooves.

[0050] FIG. 8 illustrates a front view of a barrel extension with feed ramps, according to one or more embodiments.

[0051] FIG. 9 illustrates a sectioned side view of a barrel extension.

[0052] FIG. 10 illustrates a top view of a loaded double stack/single feed configured magazine, according to one or more embodiments.

[0053] FIG. 11 illustrates a rear view of an unloaded double stack/single feed configured magazine, according to one or more embodiments.

[0054] FIG. 12A illustrates a rear view of a loaded double stack/single feed configured magazine, according to one or more embodiments.

[0055] FIG. 12B illustrates potential failure zone forces on cartridges and magazine bodies in a narrow double stack cartridge configuration, according to one or more embodiments.

[0056] FIG. 13A illustrates a rear view of a loaded double stack/single feed configured magazine, according to one or more embodiments.

[0057] FIG. 13B illustrates failure zone forces on cartridges and magazine bodies in a wide double stack cartridge configuration, according to one or more embodiments.

[0058] FIG. 14 illustrates top, side, and rear views of a double stack/single feed magazine, curved with stiffening grooves, according to one or more embodiments.

[0059] FIG. 15 illustrates top, side, and rear views of a double stack/single feed magazine, straight with stiffening grooves, according to one or more embodiments.

[0060] FIG. 16 illustrates top, side, and rear views of a double stack/single feed magazine, curved without stiffening grooves, according to one or more embodiments.

[0061] FIG. 17 illustrates top, side, and rear views of a double stack/single feed magazine, straight without stiffening grooves, according to one or more embodiments.

[0062] FIG. 18 illustrates a magazine including a narrow double stack section and a wide double stack section.

[0063] FIG. 19 illustrates cartridge path locations on a sectioned side view of a barrel extension.

[0064] FIG. 20 illustrates a side perspective view of a bolt carrier, according to one or more embodiments.

[0065] FIG. 21 illustrates a bottom perspective view of the bolt carrier, according to one or more embodiments.

[0066] FIG. 22A illustrates a front perspective view of the bolt carrier, according to one or more embodiments.

[0067] FIG. 22B illustrates a front perspective view of the bolt carrier and a double stack/double feed magazine, according to one or more embodiments.

[0068] FIG. 22C illustrates a front perspective view of the bolt carrier and a double stack/single feed magazine, according to one or more embodiments.

[0069] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one or more embodiments may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0070] Embodiments described herein generally relate to firearm magazines and a corresponding bolt carrier assembly. More specifically, embodiments described herein relate to a magazine design that allows for the advantages of a double stack magazine for high capacity while utilizing a single feed style mechanism for positioning and guiding the cartridges into the chamber. The firearm magazine includes a magazine body having a width to accommodate a double stack of cartridges in a zigzag pattern. The magazine includes a spring coupled to a follower within the magazine body. The firearm magazine body includes two feed lips coupled to the magazine body. The two feed lips are configured to simultaneously hold a single cartridge in place in a center of the magazine body to allow a bolt carrier to push the single cartridge out of the firearm magazine and into a chamber of a firearm. The bolt carrier includes feed lip channels configured to accommodate the feed lips therein. A cocking surface is located between the feed lip channels and has a width of less than about 0.400 inches.

[0071] Embodiments described herein maintain the double stack configuration for the loaded cartridges but utilize a single feed design instead of the traditional double feed design. As mentioned previously, the double feed design has two feed lipsone on each side of the magazine which holds the top cartridge in each stack in place. Therefore each feed lip retains one cartridge (e.g., the top cartridge is retained by one feed lip). The double stack/single feed design has one set of feed lips that position one cartridge in the center top of the magazine. Therefore, both feed lips retain a single cartridge in the center position. The feed lips of the single feed design are curved to direct the cartridges into the single feed position but do not need to be shaped to match the curvature of the cartridge case. Instead, the feed lips are angled inward from each side of the magazine at an angle that best guides the cartridges, depending on diameter, from each stack into the center of the magazine and into the single feed position.

[0072] Embodiments described herein may utilize a narrow double stack cartridge configuration or a wide double stack cartridge configuration. In the narrow double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches two other cartridges, except for the top and bottom cartridges, which only contact one other cartridge (see, e.g., FIG. 12A).

[0073] In the wide double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches three or four other cartridges, except for the top and bottom cartridges, which may only touch one or two other cartridges (see e.g., FIG. 13A).

[0074] In another embodiment, a magazine body may comprise a first section with a first width where the cartridges are arranged in a narrow double stack cartridge configuration, and may also comprise a second section with a second width where the cartridges are arranged in a wide double stack cartridge configuration, as discussed with respect to FIG. 18 below.

[0075] FIG. 10 illustrates a top view of a loaded double stack/single feed configured magazine, according to one or more embodiments described herein. Magazine 300 contains a magazine body 302 and feed lips 308. As shown, cartridge 114 is centered in the magazine 300 when it is at the top of the magazine 300 and is the next cartridge 114 to be fed into the chamber of the firearm.

[0076] The double stack magazine 300 with a single feed design utilizes a similar internal design to store the cartridges as the double stack/double feed high capacity magazine described above in FIGS. 1A and 2-7. The double stack/single feed magazine 300 has two vertical columns of cartridges 114 located next to each other arranged in a zigzag type configuration. The single feed magazine design also utilizes a similar coil type magazine spring on the inside that extends from the top of the magazine to the bottom, and which utilizes a follower on the top of the spring to guide the cartridges 114 as they are loaded into the magazine.

[0077] FIG. 11 illustrates a rear view of an unloaded double stack/single feed configured magazine 300, according to an embodiment. The inside of the magazine body 302 contains a follower 306 coupled to magazine spring 304. The magazine spring 304 extends from a floor plate 312 to the top of the magazine 300, and is compressed when cartridges 114 are loaded into the magazine 300. Feed lips 308 and bolt channel 310 are also illustrated in FIG. 11. In one or more embodiments, a width of the bolt channel 310 between the feed lips 308 is in a range from about 80% to about 90%, for example about 85%, of the diameter of the cartridges 114 in the magazine 300.

[0078] FIG. 12A illustrates a rear view of a loaded double stack/single feed configured magazine 300 with a narrow double stack, according to an embodiment. Cartridges 114 are loaded within magazine body 302. The magazine spring 304 is compressed and extends from floor plate 312 to follower 306, which is in contact with the bottom-most cartridge 114 in magazine 300. Feed lips 308 are configured to center the top cartridge 114 into bolt channel 310 so that the top cartridge 114 can be fed into the chamber.

[0079] In the narrow double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches two other cartridges, except for the top and bottom cartridges, which only contact one other cartridge. In the narrow double stack cartridge configuration, the width of the cartridge stack is approximately less than 150% of the diameter of the cartridge case. Thus, the width of the cartridge stack is outside of the failure zone as described above.

[0080] FIG. 13A illustrates a rear view of a loaded double stack/single feed configured magazine 350 with a wide double stack, according to an embodiment. Cartridges 114 are loaded within magazine body 352. As shown, spring 354 is compressed and extends from floor plate 362 to follower 356, which is in contact with the bottom-most cartridge 114 in magazine 350. Feed lips 358 are configured to center the top cartridge 114 into bolt channel 360 so that the top cartridge can be fed into the chamber.

[0081] In the wide double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches three or four other cartridges, except for the top and bottom cartridges, which may only touch one or two other cartridges. In the wide double stack cartridge configuration, the width of the cartridge stack is greater than 180% of the diameter of the cartridge case. Thus, the width of the cartridge stack is outside of the failure zone as described above.

[0082] Although the double stack/single feed magazine designs illustrated in FIGS. 12A and 13A maintain the double stack configuration, the single centered feed location allows the width of the double stack of cartridges to be altered to maximize the stack geometry without affecting the functioning of the magazine. The altered stack geometry allows a fixed size magazine to accept a larger range of cartridge diameters.

[0083] The single feed design also requires less force from the bolt as the firearm cycles because the cartridge is easily fed from the magazine and into the chamber with less resistance. The double feed design, in contrast, requires more force from the bolt to overcome the resistance created when the cartridges engage the feed ramps and are redirected into the chamber. As the projectile in the cartridge engages the feed ramp as the cartridge moves forward, the rear half of the cartridge case is still under the feed lip. As the front of the cartridge is deflected up due to the contact with the feed ramp, the rear of the cartridge is deflected down and must push the remaining cartridges in the magazine down and compress the magazine spring until the rear of the cartridge is pushed out from under the feed lip. This movement also causes resistance on the bolt as the cartridge is fed from the magazine.

[0084] The double stack/single feed magazine functions in much the same manner as a traditional double stack/double feed magazine in that the cartridges are removed or stripped from the magazine by the bolt as the firearm cycles. Both designs utilize a magazine spring that pushes the cartridges up from the bottom of the magazine and feeds them as the firearm cycles, while the cartridges are retained in the magazine by the feed lips at the top of the magazine.

[0085] The double stack/single feed design, however, allows the magazine feed lips to present the cartridge in a centered and more elevated position when compared to a traditional double stack/double feed design. A comparison of FIGS. 1A and 13A illustrates the difference of the position of the top cartridge in the magazine between the double feed design (FIG. 1A) and the single feed design (FIG. 13A). The elevated and centered location in the single feed design positions the cartridge more in line with the chamber of the firearm and allows the cartridge to be stripped or fed from the magazine by the bolt and directly into the chamber with less opportunity for the projectile to contact any feed ramps or bolt lug recesses or any other parts of the firearm.

[0086] Cartridges fed from a magazine with a single feed design are generally more accurate than those from a traditional double feed design because the projectiles are not damaged as the cartridges are fed from the magazine and into the chamber.

[0087] FIG. 14 illustrates top, side, and rear views of a double stack/single feed magazine 300, curved with stiffening grooves 316, according to an embodiment. As seen in the side view of the magazine 300, the magazine 300 is curved and includes a number of stiffening grooves 316. The feed lips 308 are also visible in the top, side, and rear views of the magazine 300. The bolt channel 310 is shown in the rear view of the magazine 300.

[0088] FIG. 15 illustrates top, side, and rear views of a double stack/single feed magazine 300, straight with stiffening grooves 316, according to an embodiment. As seen in the side view of the magazine 300, the magazine 300 is straight from the top to the bottom and includes a number of stiffening grooves 316. The feed lips 308 are also visible in the side and rear views of the magazine 300. The bolt channel 310 is shown in the rear view of the magazine 300.

[0089] FIG. 16 illustrates top, side, and rear views of a double stack/single feed magazine 300, curved without stiffening grooves, according to an embodiment. As seen in the side view of the magazine 300, the magazine 300 is curved. The feed lips 308 are also visible in the side and rear views of the magazine 300. The bolt channel 310 is shown in the rear view of the magazine 300.

[0090] FIG. 17 illustrates top, side, and rear views of a double stack/single feed magazine 300, straight without stiffening grooves, according to an embodiment. As seen in the side view of the magazine 300, the magazine 300 is straight from the top to the bottom. The feed lips 308 are also visible in the side, top, and rear views of the magazine 300. The bolt channel 310 is shown in the rear and top view of the magazine 300.

[0091] FIG. 18 illustrates an example of a double stack/single feed magazine 400, according to another embodiment. The magazine 400 comprises feed lips 408 atop a magazine body 402. Floor plate 412, spring 404, and follower 406 are also illustrated. In this embodiment, the magazine body 402 is larger at the bottom of the magazine 400 than at the top. Therefore, the stack geometry of the cartridges 114 in the magazine 400 contains cartridges 114 in a wide or standard double stack pattern at the bottom of the magazine 400 and cartridges 114 in a narrow double stack pattern at the top of the magazine 400. In one or more embodiments, the bottom portion of the magazine 400 is approximately 20% wider than the top portion of the magazine 400. In another embodiment, the bottom portion of magazine 400 is greater than 20% wider than the top portion of the magazine 400.

[0092] The structure of the magazine 400 allows the narrower top portion of the magazine 400 to fit into an existing smaller magazine well of a firearm, while the wider bottom portion allows for more cartridges to fit into the magazine 400.

[0093] FIG. 19 illustrates cartridge path locations on a sectioned side view of a barrel extension 200. A chamber 204 is shown in barrel 210. Feed ramps 202 are also illustrated. As described with respect to FIG. 9 above, a lower projectile position 220 for a double feed magazine is illustrated with an arrow. Also illustrated in FIG. 19 with an arrow is an upper projectile position 230 for a single feed magazine. In a double feed magazine, the tip of the projectile is located in the lower projectile position 220. In this lower projectile position 220, the projectile may miss the leading edge of the feed ramp 202 and stop moving forward when the projectile hits the flat inside surface of the barrel extension 200 or upper receiver, thereby causing a feed jam and causing the firearm to malfunction. However, with a single feed magazine according to the embodiments described herein, the tip of the projectile is located in the upper projectile position 230. In this position, the cartridge will not hit the flat surface of the barrel extension 200 and stop moving forward. Instead, the cartridge is more likely to clear the barrel extension 200 and be loaded into the chamber 204 of the firearm without being obstructed or damaged. Therefore the double stack/single feed magazine as described herein provides an advantage over the conventional double stack/double feed magazine.

[0094] To disassemble one or more embodiments of the double stack/single feed magazine as described herein, the floor plate is removed by sliding the floor plate to the front or rear and off of the bottom of the magazine. Then, the coil spring and follower are removed by pulling them out the bottom of the magazine. Assembly of the magazine is in reverse order of disassembly.

[0095] Due to the single feed position in the center of the magazine having a bolt channel narrower than the cartridge case, loading of the cartridges must occur one at a time with the cartridges pushed into position from the front, which depresses the follower and slides the cartridge down and under the feed lips. Additional cartridges are fed the same way by depressing the cartridge that is already in the magazine down and sliding the next cartridge into the magazine on top of the one already in the magazine. The magazine is unloaded by sliding the cartridges out from under the feed lips from back to front one at a time until the magazine is empty.

[0096] FIG. 13B illustrates forces 510 in a wide double stack magazine. In the wide double stack magazine, the magazine body 502 contains the cartridges 114. The forces 510 in the wide double stack magazine are generally straight up and down, and do not push against the sides of the magazine body.

[0097] FIG. 12B illustrates potential forces 512 in a narrow double stack magazine. The body 504 of the narrow double stack magazine contains cartridges 114. Forces 512 push outward against the body 504. The forces 512 can wedge the cartridges 114 in place, depending on the magnitude of the forces 512 and the angle of the forces 512. The forces 512 can cause the magazine to fail if the magazine is not constructed to accommodate the proper width of the cartridge stack. As described above, the failure or wedge zone where the cartridges 114 exert forces to the outside walls of the magazine is approximately 150% to 180% of the diameter of the cartridge case. Previous attempts to adapt larger cartridges to existing magazines have resulted in failure because the width of the stack of cartridges falls in the failure zone.

[0098] FIG. 20 illustrates a side perspective view of a bolt carrier 600, according to one or more embodiments. The bolt carrier 600 includes a body 602 with a first end 620 and a second end 622 opposite the first end 620. A stepped surface 606 is formed in the body 602 adjacent to the first end 620. The stepped surface 606 may be used to engage a charging handle (not shown) to manually cycle the bolt rearward in the firearm assembly. A cocking surface 612 is formed in the body 602 adjacent to the first end 620 of the body 602. The cocking surface 612 is opposite the stepped surface 606 of the body 602. In one or more embodiments, each end of the cocking surface 612 is beveled. A feed lip groove is formed on either side of the cocking surface 612. In some embodiments, the feed lip grooves define at least a portion of the cocking surface 612. The feed lip grooves are discussed in more detail below.

[0099] A recess 608 is formed into a side of the body 602. One or more gas exhaust ports 610 are formed in the recess 608. The one or more gas exhaust ports 610 enable a gas pressure built up inside the body 602 to be exhausted outside the firearm. An opening 618 formed in the body 602 adjacent to the plurality of forward assist notches 614 enables excess gas inside the bolt carrier 600 to be exhausted outside the firearm. A firing pin retaining hole 616 is also formed in the body 602 adjacent to the plurality of forward assist notches 614. The firing pin retaining hole 616 enables a firing pin retaining pin (not shown) to be inserted to retain a firing pin (not shown) of the firearm inside the bolt carrier 600.

[0100] The body 602 is generally cylindrical in shape, as depicted in FIG. 20. The body 602 is configured to have a bolt (not shown) inserted into the bolt carrier at the first end 620. A plurality of forward assist notches 614 is formed in a side of the body 602. The notches 614 are engaged by a forward assist (not shown) in the firearm assembly to force the bolt carrier 600 forward so that the bolt in the bolt carrier 600 engages the barrel extension lugs 212 illustrated in FIG. 9.

[0101] A bolt (not shown) is inserted into the first end 620 of the bolt carrier 600. As the bolt carrier 600 cycles in the firearm, the bolt moves with the bolt carrier 600. The bolt is held in the bolt carrier 600 via a cam pin (not shown). The cam pin is retained in the bolt carrier 600 by a firing pin (not shown) which is inserted into the second end 622 of the bolt carrier 600. The firing pin is held in the bolt carrier 600 by a firing pin retaining pin (not shown). The assembled combination of the bolt carrier 600 along with components which are not illustrated, such as the bolt, the cam pin, the firing pin, and the firing pin retaining pin are referred to as a bolt carrier group.

[0102] When a cartridge 114 is fired, the bolt carrier 600 moves from a forward position to a rearward position to eject an empty cartridge case. As the bolt carrier 600 moves to the rearward position, the cocking surface 612 contacts and cocks a hammer (not shown) in the firearm. Once in the rearward position, the bolt carrier 600 moves to the forward position, passing over the magazine 300. As the bolt carrier 600 passes over the magazine 300, the top cartridge 114 in the magazine 300 is pushed or stripped from the magazine 300 toward the barrel extension 200.

[0103] FIG. 21 illustrates a bottom perspective view of the bolt carrier 600, according to one or more embodiments. The cocking surface 612 is disposed between feed lip grooves 624. The feed lip grooves 624 are formed in the body 602 and extend from the first end 620 of the body toward the second end 622 of the body. In one or more embodiments, the feed lip grooves 624 are recesses formed into the body 602. The feed lip grooves 624 are shaped to accommodate a magazine feed lip, such as the feed lips 308 illustrated in FIG. 10.

[0104] A width 629 of the cocking surface 612 is configured to enable the bolt carrier 600 to be used with a double stack/single feed magazine 300 designed for various cartridge sizes. A width of the bolt channel 310 corresponds to a diameter of the cartridges 114 loaded in the magazine 300. That is, as the size of cartridges 114 in the magazine 300 increases, the width of the bolt channel 310 between the feed lips 308 of the magazine 300 also increases. In one or more embodiments, the width of the bolt channel 310 is in a range from about 80% to about 95% of the diameter of the cartridge loaded in the magazine 300, such as a range from about 82% to about 90%, for example, about 85%. For example, the width of the bolt channel 310 is about 0.321 inches for a cartridge 114 having a diameter of about 0.378 inches; the width of the bolt channel 310 is about 0.359 inches for a cartridge 114 having a diameter of about 0.422 inches; the width of the bolt channel 310 is about 0.374 inches for a cartridge 114 having a diameter of about 0.440 inches; the width of the bolt channel 310 is about 0.380 inches for a cartridge 114 having a diameter of about 0.447 inches.

[0105] As the width of the bolt channel 310 is modified to accommodate various diameters of the cartridge 114, the width 629 of the cocking surface 612 is also modified to accommodate the various widths of the bolt channel 310. For example, a conventional bolt carrier for an AR15/M4 style rifle has a cocking surface with a width of about 0.400 inches. To enable use of the bolt carrier 600 with a double stack/single feed magazine 300, the width 629 of the cocking surface 612 is reduced to less than 0.400 inches, such as in a range from about 0.200 inches to 0.380 inches, for example, about 0.300 inches. That is, the width 629 of the cocking surface 612 should be less than a width of the bolt channel 310 between the feed lips 308 of the magazine 300.

[0106] A recess 626 is formed in a rear section 604 of the bolt carrier 600. A tapered portion 628 of the bolt carrier 600 is formed at an end of the cocking surface 612 opposite the first end 620 of the bolt carrier 600. The tapered portion 628 is configured to contact the hammer of the firearm when the bolt carrier 600 moves toward the rearward position. The tapered portion 628 enables the hammer to be pushed downward to begin cocking the hammer. The cocking surface 612 completes cocking the hammer by pushing the hammer downward into a cocked position.

[0107] FIG. 22A illustrates a front perspective view of the bolt carrier 600, according to one or more embodiments. As shown, the feed lip grooves 624 are formed in the body 602. The feed lip grooves are recesses formed into a bottom surface of the bolt carrier 600. A protrusion 654 is formed between the feed lip grooves 624. The cocking surface 612 is disposed on the protrusion 654 at a distance 652 from a central axis 650 of the bolt carrier 600. The central axis 650 extends along the bolt carrier substantially parallel to the feed lip grooves 624 and the cocking surface 612. The distance 652 is in a range from about 0.25 inches to about 0.5 inches, such as in a range from about 0.35 inches to about 0.40 inches, for example, about 0.37 inches. In some embodiments, a maximum width of the cocking surface 612 is about 0.39 inches. In other embodiments, the width of the cocking surface is from about 0.39 inches, about 0.38 inches, about 0.37 inches, 0.36 inches, or 0.35 inches to about 0.3 inches, 0.25 inches, 0.2 inches, or about 0.1 inches. For example, the width of the cocking surface may be from about 0.37 to about 0.25, such as, about 0.35 inches.

[0108] In some embodiments, the cocking surface 612 is substantially tangential to the bolt carrier 600. The cocking surface 612 and the protrusion 654 may be fabricated with various profiles. In some embodiments, the cocking surface 612 is a surface of the protrusion 654 that is farthest from the central axis 650 and opposite the stepped surface 606 illustrated in FIG. 20. The cocking surface 612 may be concave, convex, pointed, substantially planar, etc. In some embodiments, the protrusion 654 is defined by two, three, four, five, or more surfaces including the cocking surface 612. In some embodiments, the cocking surface 612 may include one or more surfaces between the feed lip grooves 624. A width of the protrusion 654 may be smaller or larger than a width of the cocking surface 612.

[0109] FIG. 22B illustrates a front perspective view of the bolt carrier 600 and a double stack/double feed magazine 630, according to one or more embodiments. The feed lip grooves 624 are configured to enable the feed lips 632 of the magazine 630 to pass therethrough as the bolt carrier 600 moves between the forward position and the rearward position. The cocking surface 612 of the bolt carrier 600 is configured to pass between the feed lips 632 of the magazine 630 as the bolt carrier 600 moves in the firearm.

[0110] FIG. 22C illustrates a front perspective view of the bolt carrier 600 and a double stack/single feed magazine 640, according to one or more embodiments. A cocking surface 615 between the feed lip grooves 624 is narrowed compared to the cocking surface 612 illustrated in FIG. 22B. The cocking surface 615 is narrowed to enable the feed lips 642 of the double stack/single feed magazine 640 to pass through the feed lip grooves 624 as the bolt carrier 600 moves between the forward position and the rearward position. In some embodiments, the cocking surface 615 is narrowed as the feed lip grooves 624 are widened.

[0111] The double stack/single feed magazine described herein has a number of advantages over conventional magazines. First, the double stack/single feed magazine maintains the high capacity design of conventional magazines. Second, the double stack/single feed magazine does not damage projectiles as much as the conventional design. Finally, the double stack/single feed magazine is easily adaptable for use with larger diameter cartridges.

[0112] The bolt carrier with a narrow cocking surface can be used with various cartridge sizes that are larger than a cartridge size of standard AR15/M4 rifles. The narrow cocking surface enables the bolt carrier to be used with a double stack/single feed magazine. The double stack/single feed magazine enables cartridges to be used that are larger than those that can be used with a double stack/double feed magazine. The combination of the double stack/single feed magazine and the narrow cocking surface enables the firearm to function properly when firing cartridges larger than the cartridges for which the firearm was designed.

[0113] Some embodiments herein discuss semiautomatic and automatic firearms, particularly semiautomatic and automatic rifles that utilize barrel extensions. Embodiments described herein may also be utilized in bolt action rifles that utilize feed ramps with appropriate modifications, if necessary. Embodiments herein may utilize any magazine capacity, from one cartridge to forty cartridges or even higher.

[0114] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated.

[0115] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.