US20200011625A1

US20200011625A1 - BOLT CARRIER FOR SEMI-AUTOMATIC and AUTOMATIC FIREARM

Info

Publication number: US20200011625A1
Application number: US16/253,988
Authority: US
Inventors: Lawrence S. Kramer
Original assignee: Kramer Cartridge & Carbine dba Kramer Defense LLC
Current assignee: Kramer Cartridge & Carbine dba Kramer Defense LLC
Priority date: 2018-07-06
Filing date: 2019-01-22
Publication date: 2020-01-09

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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 16/029,317, filed on Jul. 6, 2018, which is incorporated herein by reference.

BACKGROUND

Field

Embodiments of the present disclosure generally relate to firearm magazines and corresponding firearm parts. More specifically, the disclosure relates to an improved high capacity magazine design that allows for the feeding of ammunition without the use of feed ramps and/or allows an existing magazine to be used for larger cartridges than the magazine's original design.

Description of the Related Art

Magazines for automatic and semi-automatic firearms are often of the high capacity design to provide the firearm with a reasonable amount of ammunition. Magazines can be comprised of metal, various polymers, or any other suitable material, including a combination of materials. Magazines may be made as one piece of folded material or as multiple sections attached together.
To maximize the use of the space inside the magazine, and to keep the magazine as small as possible, the ammunition is often arranged in a “double stack” configuration to reach the high capacity desired. Double stack refers to the two vertical columns of cartridges arranged next to each other in a staggered zigzag pattern (see FIG. 1A) when the magazine is loaded. The magazines are also configured in a “double feed” configuration. That is, the double feed design has two feed lips—one on each side of the magazine which holds the top cartridge in each stack in place. Each feed lip of the double feed design retains one cartridge. FIG. 1A illustrates a magazine 100 utilizing a double stack/double feed configuration. The cartridges 114 are arranged inside the magazine body 102 as illustrated. These two columns of cartridges 114 extend from the top to the bottom of the magazine 100 when the magazine 100 is fully loaded.
The magazine 100 has a coil type spring 104 on the inside of the magazine 100 that extends from the bottom of the magazine 100 to the top. A floor plate 112 is at the bottom of the magazine 100. On top of the spring 104 is a plastic or metal piece called a follower 106 formed to guide the cartridges 114 into place as the cartridges 114 are loaded into the magazine 100. As the magazine 100 is loaded, the spring 104 compresses until the magazine 100 is fully loaded. The cartridges 114 are contained inside the magazine 100 by feed lips 108 at the top of the magazine 100. There are two feed lips 108 on a double stack/double feed configured magazine, one on each side of the magazine. The feed lips 108 are curved pieces of metal or plastic that are attached to and extend from the sides of the magazine 100. The feed lips 108 are curved at a desired angle to maintain the top-positioned cartridge 114 in position in the magazine 100. As shown in FIG. 1A, each feed lip 108 retains one cartridge 114: the cartridge 114 that is on the side of the magazine 100 that the respective feed lip 108 is on. In this example, the left feed lip 108 is retaining the topmost cartridge 114 in the magazine 100. After the topmost cartridge 114 is removed from the magazine 100 and chambered into the firearm, the next highest cartridge 114 at the top of the right side stack of cartridges 114 moves into the topmost position in the magazine 100 and held in position by the right feed lip 108.
The cartridges 114 are held up against the underside of feed lips 108 by the upward force exerted by the magazine spring 104. There is a space (e.g., a bolt channel 110) between the inside edges of the two feed lips 108 to allow a bolt of the firearm to pass through as the bolt moves forward and pushes the cartridges 114 out of the magazine 100 and into the chamber of the firearm.
FIG. 1B illustrates a magazine 150 having a single stack/single feed configuration. Cartridges 114 are arranged in a single vertical stack within the magazine body 102. Feed lips 108 both hold the topmost cartridge 114 at the top of the magazine 150, with the bolt channel 110 between the feed lips 108. The follower 106, the spring 104, and the floor plate 112 operate similarly to the double stack/double feed magazine described above in FIG. 1A. A single stack/single feed magazine is generally thinner than a double stack/double feed magazine of similar length and caliber, but the single stack/single feed magazine holds fewer cartridges.
FIG. 2 illustrates a top view of double stack/double feed magazine 100. As shown, the cartridges 114 are arranged in a staggered zigzag pattern within the magazine body 102. The bolt channel 110 is shown between the feed lips 108. During operation, the cartridges 114 are removed or “stripped” from the magazine 100 by the bolt of the firearm as the bolt cycles back and forth during firing. The bolt removes the top cartridge 114 in magazine 100 each time a cartridge 114 is fired. A cartridge 114 is removed from one side of the magazine 100 and then a cartridge 114 is removed from the other side of the magazine 100, in an alternating pattern, until the magazine 100 is empty. As shown in FIG. 2, the feed lip 108 on the left is holding the top cartridge 114 in place.
FIG. 3 illustrates an empty double stack/double feed magazine 100 containing no cartridges 114. Spring 104 is extended from the bottom of the magazine 100 (near floor plate 112) to the top of the magazine 100, where the follower 106 is shown near the feed lips 108 and the bolt channel 110.
FIG. 4 illustrates top, side, and rear views of a double stack/double feed magazine 100, curved with stiffening grooves 116. As seen in the side view of the magazine 100, the magazine 100 is curved and includes a number of stiffening grooves 116. The feed lips 108 are also visible in the top, side, and rear views of the magazine 100. The bolt channel 110 is shown in the rear and top view of the magazine 100.
FIG. 5 illustrates top, side, and rear views of a double stack/double feed magazine 100, straight with stiffening grooves 116. As seen in the side view of the magazine 100, the magazine 100 is straight from the top to the bottom, and includes a number of stiffening grooves 116. The feed lips 108 are also visible in the side and rear views of the magazine 100. The bolt channel 110 is shown in the rear and top view of the magazine 100.
FIG. 6 illustrates top, side, and rear views of a double stack/double feed magazine 100, curved without stiffening grooves. As seen in the side view of the magazine 100, the magazine 100 is curved. The feed lips 108 are also visible in the top, side, and rear views of the magazine 100. The bolt channel 110 is shown in the rear and top view of the magazine 100.
FIG. 7 illustrates top, side, and rear views of a double stack/double feed magazine, straight without stiffening grooves. As seen in the side view of the magazine 100, the magazine is straight. The feed lips 108 are also visible in the side and rear views of the magazine 100. The bolt channel 110 is shown in the rear and top view of the magazine 100.
Conventional double stack/double feed magazines have several benefits, such as maximizing the space available to contain as many cartridges as possible while keeping the magazine as small as possible. However, there are also drawbacks to the conventional double stack design. As mentioned above, double stack configured magazines utilize a feed lip on each side of the magazine to contain and align the cartridges in a horizontal tip forward position.
The chamber of a firearm is located in the center of the barrel. A double stack/double feed configured magazine presents the cartridges in a low offset position as the cartridges relate to the chamber of the firearm, with each stack of cartridges off to a side of and just below the chamber, as illustrated in FIGS. 1A and 2. For the cartridges from the two columns in the magazine to enter the chamber correctly, the cartridges must be directed into the chamber from the cartridge's offset positions in the magazine.
FIG. 8 illustrates a front view of a barrel extension 200 with feed ramps 202. The cartridges in a double stack/double feed magazine are directed into the chamber of the firearm by feed ramps 202 located directly in front of the top cartridge on each side of the magazine. These feed ramps 202 are angled channels or ramps machined into the barrel extension 200 attached to the barrel of the firearm and are used to guide the cartridges into the chamber 204 as the cartridges are pushed forward and out of the magazine by the bolt. As the bolt cycles, the top cartridge located under the feed lip of the magazine is pushed forward by the bolt of the firearm, and the cartridge moves in a straight horizontal fashion until the projectile in the cartridge contacts the beveled feed ramp 202 on the barrel extension 200. As the cartridge continues to move forward the cartridge is deflected upward and inward towards the center line of the firearm and into the chamber 204 of the firearm.
When the cartridge is pushed forward by the bolt as the firearm cycles, the cartridge is moved with a great amount of force and velocity. When the projectile in the cartridge engages the steel feed ramp 202 with this force, the tip of the projectile can be dented or deformed which degrades the aerodynamic properties of the projectile thereby reducing accuracy of the projectile.
Additionally, hunters often use soft point ammunition with exposed soft lead tips that are required for hunting and that accelerate the expansion of the projectile. These exposed lead tips can be severely damaged by the feed ramps 202, degrading the accuracy of the hunting ammunition and resulting in wounded or wasted animals.
Another drawback to the use of feed ramps 202 in barrel extensions 200 of semi-automatic and automatic firearms to deflect and direct the cartridges into the chamber 204 of the firearm is that each feed ramp 202 is located just below a bolt lug recess cut into the barrel extension 200. Bolt lug recesses 206 are illustrated in FIG. 8. The barrel extension 200 is a round metal collar screwed onto the back of the barrel that has teeth or “lugs” 212 that give the bolt of the firearm something to lock into to contain the high pressures of the cartridge when the cartridge is fired. Between each barrel extension lug 212 of the barrel extension 200 is a recess 206 or slot that allows passage of the lugs on the bolt to pass through as the bolt enters the barrel extension 200 and locks thereinto. In one or more embodiments, each of the lugs on the bolt corresponds to at least one of the bolt lug recesses 206 of the barrel extension 200. In some embodiments, each of the lugs on the bolt corresponds to one of the bolt lug recesses 206 of the barrel extension 200.
The bolt lug recesses 206 have a square shape with sharp edges 208 on all three sides. As the cartridge is deflected into the chamber, the projectile impacts the feed ramps 202 and passes through the bolt lug recess 206. As the cartridge passes through, the projectile often comes into contact with the sharp edges 208 which can further damage the jacket of the projectile and further degrade the projectile's accuracy. The damage to the projectile by the barrel extensions' sharp lug recess edges 208 becomes more severe as the caliber of the projectile increases. Smaller caliber projectiles that are close to the width of the recess 206 may pass through with little or no damage, but larger caliber projectiles can receive major damage as the large projectile attempts to pass through the narrow recess 206. Feeding of large projectiles can even cause enough of a drag as the projectile's jacket digs into the sharp edges of the recess 206 to slow down the bolt of the firearm and cause the firearm to malfunction.
Military and law enforcement snipers as well as civilian competition shooters often prefer semiautomatic rifles and use match ammunition loaded with match grade projectiles that deliver excellent accuracy at extreme distances. Match grade projectiles are manufactured to exacting tolerances for consistency, including almost identical weights, jacket thickness concentricity, aerodynamic profiles, and perfectly formed tips. When these match grade projectiles engage the steel feed ramps 202 and sharp edges 208 of the bolt lug recesses 206, the match grade projectiles are often deformed which is detrimental to the precision design of the match grade projectiles and defeats the intended purpose of the match grade projectiles for improved long range accuracy. Degraded accuracy of match ammunition used by military and law enforcement snipers could mean the difference between life and death for a hostage or bystanders.
The most common semiautomatic firearm in use today by the military, law enforcement and civilian shooters is the AR15 (or AR10) style rifle. One of the reasons for the popularity of the AR15 style rifle is the modular two piece design of the AR15 style rifle which allows the upper and lower receivers to be exchanged with alternative upper or lower receivers. This modular design allows the owner of one lower receiver to have multiple upper receivers, and therefore multiple calibers for one firearm. The lower receiver contains the magazine well, which is the recess where the magazine is inserted into the firearm. The magazine well is a fixed size and only accepts one size of magazine.
While the upper receiver of the firearm can be replaced easily to change from one caliber or cartridge to another, altering the magazine to accept additional cartridges is not as easy. The double stack/double feed design magazines for AR15 type (or AR10) rifles have been slightly modified successfully to accept several slightly larger cartridges, but the double stack design magazine also has limitations to the size of cartridges the double stack magazine can accept. The two major limiting factors are feed lip adaptability and stack geometry.
As discussed above, feed lips 108 are metal flaps attached to the sidewall of the magazine 100 that are bent over the top of the magazine 100 to contain the cartridges 114 inside the magazine 100 and to help guide the cartridges 114 into the chamber 204. Feed lips 108 are curved at an angle to retain the cartridge, for which the magazine was designed, in the magazine. There is also a minimum amount of space required between the feed lips 108 for the bolt of the firearm to pass through the bolt channel 110 as the bolt pushes the cartridges 114 out of the magazine 100 and into the chamber 204 (see, e.g., FIGS. 1A, 2, and 8).
In one or more embodiments, a cartridge includes a case (not shown), a projectile (not shown), an ignition source (not shown), and a propellant (not shown). In one or more embodiments, the case is fabricated from a brass containing material. The case is cylindrical in shape and at least partially defines a volume therein. The ignition source is disposed at the first end of the case. The propellant is disposed in the volume. The projectile is at least partially inserted in the second end of the case. A diameter of the cartridge is a largest diameter of the case between the first end and the second end.
As the cartridge case gets larger in diameter, the width of each feed lip 108 must also be increased to securely hold the larger case in place. As the width of the feed lips 108 is increased, the width between the two feed lips 108 is reduced. The width between the two feed lips 108 determines the “bolt channel” 110, which is required for the firearm to operate, and thus limits the diameter of the cartridge case the double stack/double feed magazine 100 can adapt to.
FIG. 9 illustrates a sectioned side view of the barrel extension 200. Barrel extension lugs 212 are visible, and the bolt lug recesses 206 are not visible but are illustrated by a dotted line. Chamber 204 is shown in barrel 210. Feed ramps 202 are also illustrated.
As the cartridge case becomes larger in diameter, the tip of the projectile is located in a lower position in relation to the feed ramp 202 when compared to a smaller diameter cartridge case because the feed lips 108 are in a fixed location and cannot be moved. For example, a lower projectile position 220 for a double feed magazine is illustrated with an arrow in FIG. 9. When the tip of the projectile is located 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.
Stack geometry refers to the way the cartridges 114 position themselves and move inside the magazine 100 when the magazine is loaded. Magazines are originally designed and built for a specific cartridge diameter. A traditional double stack type of magazine has a width to accommodate two vertical columns of selected cartridges side by side in a zigzag pattern from top to bottom, as illustrated in FIG. 1A. With “good stack geometry,” the entire stack of cartridges moves freely up and down inside the magazine with virtually no outward forces or resistance in the magazine. As such, the cartridges “feed” correctly into the firearm and the magazine is reliable. FIG. 13B illustrates a double stack magazine where the forces on the cartridges 114, such as force 510, are generally vertical within the magazine body 502. The vertical forces 510 enable the cartridges 114 to move up and down inside the magazine body 502 and feed correctly.
The width of the cartridge stack in a traditional double stack magazine is approximately 188% of the diameter of the cartridge case. In this configuration, each cartridge in the stack, except for the top and bottom cartridges, is touching at least two other cartridges in the stack. Some of the cartridges may touch three or four other cartridges in the stack.
As mentioned above, the magazine has a predetermined physical size to which the magazine is limited to accommodate the magazine well of the firearm. When attempting to modify the magazine to accept larger diameter cases, the “stack geometry” inside the magazine changes. The internal dimensions of the magazine cannot be made larger or modified much because the double feed configuration requires a cartridge under each feed lip 108 on each side of the magazine. As the cartridge cases get larger in diameter, the cartridge cases have larger spaces therebetween when the magazine is loaded, which creates an outward force on the sides of the magazine. FIG. 12B illustrates forces 512 that can create an outward force on the sides of the magazine when the magazine is loaded with cartridges having a diameter larger than what the magazine was designed for, or when the width of the magazine is narrower than a conventional double stack magazine.
When this happens, the cartridges in the magazine do not move up and down freely inside the magazine and can actually cause a bulge in the outer walls of the magazine. This can cause the cartridges to jam together inside the magazine, causing a feed jam and the firearm to malfunction. This bulging of the magazines side walls also makes it difficult to insert and release the magazine from the firearm. Double stack/double feed types of magazines can therefore be modified to accept cartridges larger than originally designed, but only minimally.
When attempting to narrow the width of the double stack of cartridges there is a width or range that alters the up and down forces of the double stack of cartridges and redirects the forces on the cartridges to the outside walls of the magazine (see, e.g., FIG. 12B).
This “failure or wedge zone” where the cartridges exert forces to the outside walls of the magazine is from 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 they have attempted to adapt the cartridges to a stack width that falls in this failure zone.
What is needed is an improved magazine design for semiautomatic and automatic rifles, as well as a design that can be adapted for bolt action rifles.

SUMMARY

The present disclosure generally relates to firearm magazines for automatic and semi-automatic firearms, and more particularly to a 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. An improved magazine design allows for the use of larger diameter cartridges other than what the magazine was originally designed for, allowing larger diameter cartridges for use in smaller firearms. In military applications, larger diameter cartridges may be more effective against armor used by opposing forces. Embodiments described herein allow an existing lower receiver to shoot larger diameter cartridges without requiring the purchase of a new weapon. An improved magazine design also utilizes a single feed design, allowing the internal width of the magazine to be adjusted to provide an efficient stack geometry without affecting the feeding of the cartridges from the magazine.
In one or more embodiments, a 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 firearm 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 position of the magazine body to allow a bolt to push the single cartridge out of the firearm magazine and into a chamber of a firearm.
In some embodiments, a bolt carrier assembly is provided and includes a body having an elongated cylindrical shape with a first end opposite a second end. The body has a central axis extending from the first end to the second end. Two feed lip grooves are 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. A cocking surface is between the feed lip grooves. The cocking surface has a width of about 0.200 inches to about 0.380 inches.
In other embodiments, a bolt carrier assembly is provided which includes a body having a first end opposite a second end. The body has a central axis extending therethrough. The body is configured to accommodate a double stack, single feed magazine. The central axis extends from the first end of the body to the second end of the body. A cocking surface is formed in the body adjacent to the first end. A width of the cocking surface corresponds to a cartridge diameter and is less than 0.400 inches.
In one or more embodiments, a firearm assembly is provided which includes a barrel having a barrel extension. A plurality of bolt lug recesses is formed in the barrel extension. The firearm assembly also includes a double stack single feed magazine having two feed lips. A bolt channel is formed between the two feed lips. The firearm assembly also includes a bolt carrier assembly which includes a body having a first end and a second end. The body has a central axis extending from the first end to the second end. The body has one or more feed lip grooves formed therein which are configured to accommodate the feed lips of the magazine therein. A cocking surface is formed in the body between the feed lip grooves. The cocking surface is substantially parallel to the one or more feed lip grooves. The cocking surface has a width of about 0.200 inches to about 0.380 inches. A bolt is disposed in the first end of the body.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

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

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

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

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

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

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

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

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

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

FIG. 9 illustrates a sectioned side view of a barrel extension.

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

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

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

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.

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

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

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.

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.

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.

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.

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

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

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

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

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

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

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

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

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.
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 lips—one 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.
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).
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.”
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Claims

What is claimed is:

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.