BACKGROUND OF THE DISCLOSURE
The AR platform of rifles and carbines, which includes the M-16, M-4, AR-15, and AR-10 series of rifles, is a popular type of firearm with a wide range of variants. In recent years, due to the expense and scarcity of certain calibers of ammunition, including NATO 5.56 mm, new AR variants capable of holding different calibers have been introduced.
One of the new AR rifle variants is designed to accept pistol or handgun ammunition, such as the popular 9 mm caliber, in place of conventional rifle ammunition, thereby allowing the use of a single caliber of ammunition for both a pistol and an AR-style rifle. Use of a single caliber of ammunition has tactical, practical, and economic advantages. Tactical and practical advantages include less weight due to less ammunition being carried by the operator, and elimination of confusion regarding what ammunition to load into the pistol or carbine in a tactical situation when seconds count. Economic advantages permit stocking of only one type of ammunition for both pistol and carbines.
However, one disadvantage of the new AR rifle variants that accept pistol ammunition is that they operate using custom designed magazines, which are not interchangeable with pistols. Moreover, the AR's lower receiver cannot simply be resized to accept standard pistol magazines since, in doing so, the AR's bolt catch assembly ceases to function, thereby eliminating an operating feature of the rifle.
The standard bolt catch assembly for AR rifles is well-known in the art. The standard bolt catch assembly is positioned at the rear end of the magazine and functions to hold the bolt open after the last round is fired. When the standard AR magazine is empty, the magazine follower is pressed upward through spring pressure, and engages a small protrusion on the bolt catch assembly. Once the protrusion is contacted by the magazine follower, the standard bolt catch assembly is moved upwards into a position to block forward motion of the bolt as it returns from the rear of the rifle, where the bolt was pushed by the gas expelled in the firing of the last round. Holding the bolt in the open position allows the operator to quickly determine that all ammunition has been expended, verify that the firing chamber is clear, and rapidly change the magazine and reload the weapon if needed.
Most pistols also incorporate a bolt catch assembly to hold the bolt open after firing the last round. But because of differences in operation and design, the standard bolt catch assembly for pistols is positioned at the front end of the magazine, not at the rear end. Correspondingly, the standard pistol magazine and its follower are designed to contact a protrusion on the pistol's bolt catch assembly at the front of the magazine, rather than the rear.
As a result, if an AR lower receiver is resized to accept a standard pistol magazine, the AR's bolt catch assembly will not work. Specifically, the bolt catch assembly for the AR style carbine, which is located at the rear end of the magazine, cannot engage the follower in a standard pistol magazine, which is designed for contact at the front end. New AR rifle variants that accept pistol ammunition therefore use custom-designed rifle magazines to accommodate the pistol rounds rather than standard pistol magazines, eliminating the advantage of interoperability.
Accordingly, an objective of this disclosure is to preserve the bolt hold-open feature of a carbine or rifle, while permitting interchangeability offered by the use of pistol magazines in the carbine.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a lower receiver having an embodiment of a bolt catch assembly as described herein.
FIG. 2 is a perspective view, front elevation view, and side elevation view of an embodiment of a bolt catch assembly as described herein.
FIG. 3 is a perspective view, front elevation view, and side elevation view of a standard pistol magazine and follower.
FIG. 4 is a perspective view of a bolt for a rifle.
FIGS. 5a and 5b are perspective views of a lower receiver and an embodiment of a bolt catch assembly as described herein in two different operational states.
FIGS. 6a and 6b are side and cross-sectional views of a lower receiver and an embodiment of a bolt catch assembly as described herein in two different operational states.
FIGS. 7-10 are perspective views of a carbine or rifle adapted to accept a magazine and ammunition for a pistol.
DETAILED DESCRIPTION
An improved bolt catch assembly for a carbine or rifle is now described in the following paragraphs and in view of the accompanying figures. The improved bolt catch assembly may be used to hold a carbine's bolt to the rear or open position after the last round has been fed from the pistol magazine into the firing chamber and discharged.
Referring first to FIG. 2, shown therein is an embodiment of an improved bolt catch assembly 200. The bolt catch assembly 200 shown in FIG. 2 includes a magazine actuator arm 201, a torsion bar 202, and a bolt catch 203. The magazine actuator arm 201, torsion bar 202, and bolt catch 203 can be a single, unitary piece of material, or can be rigidly coupled to one another such that a physical force imparted on the magazine actuator arm 201 is translated to the torsion bar 202 and to the bolt catch 203.
The magazine actuator arm 201 may be formed as a solid, planar body, with a protrusion 205 projecting from the plane of the body of the magazine actuator arm 201. The protrusion 205 may be perpendicular to the magazine actuator arm 201, or it may be angled. The magazine actuator arm 201, and more specifically the protrusion 205, if present, may physically engage a magazine follower. For example, the magazine actuator arm 201 may engage the hold-open tab 303 on the magazine follower 302 for the pistol magazine 300 shown in FIG. 3.
Also shown in the embodiment showing in FIG. 2 is an optional component referred to herein as over-travel arm 204. As shown in FIG. 2, the over-travel arm 204 may be physically unitary with the magazine actuator arm 201. Alternatively it may be a separate piece attached, preferably rigidly, to the magazine actuator arm 201. The function and operation of over-travel arm 204 will be described in greater detail below.
The torsion bar 202 may be linear in shape, and may have different cross-sectional profiles, including round, square, or hexagonal. Alternative embodiments of the torsion bar 202 may have a curved or bent shape, for example the torsion bar forms an “L” shape to accommodate the configuration of the rifle lower receiver. As shown in FIG. 2, the torsion bar 202 is connected to the magazine actuator arm 201, preferably in a rigid manner. As further shown in FIG. 2, the torsion bar 202 is also connected to the bolt catch 203, again preferably in a rigid manner. The torsion bar 202 may be connected to the magazine actuator arm 201 or bolt catch 203 through various means, including welding, forging, pins, or set screws.
Similar to the standard bolt catch assembly for rifles, the bolt catch 203 may be formed as solid planar body. The bolt catch 203 may possess a bolt contact surface 206 to make contact with and engage a bolt. For example, the bolt contact surface 206 may contact and engage feed lip 401 of the bolt 400 of the carbine shown in FIG. 4. Additionally, the barrel-facing side of bolt contact surface 206 may be sloped in shape, tapering so as to reduce the possibility of the bolt catching or sticking on the bolt contact surface 206 when the bolt moves rearwards. Also similar to the standard bolt catch assembly for rifles, the bolt catch 203 may have a lever 207. As shown in FIG. 2, the lever 207 may be contacted (i.e. pressed) by an operator to actuate the bolt catch assembly 200 and permit the bolt 400 to be released and move forward. Finally, as illustrated in FIG. 2, the bolt catch 203 may remove the protrusion present in a standard bolt catch assembly for rifles used to contact a standard rifle follower.
Referring now back to FIG. 1, an improved bolt catch assembly 200 is shown positioned within the lower receiver 100 of a rifle that accepts a standard pistol magazine. FIG. 1 shows that the bolt catch assembly 200 may be secured to the side elevation of the lower receiver 100. As shown in the embodiment, this can be accomplished by the installation of a cover plate 101 with a channel in it to accept the bolt catch assembly 200 within it. The cover plate 101 may be secured to the side of the lower receiver 100. Alternative means of securing the bolt catch assembly 200 to the lower receiver 100 could include using bands, or installing the bolt catch assembly 200 directly in the lower receiver 100, or installing it in a channel in the lower receiver and securing it in the channel with set screws. As shown in FIG. 1, the bolt catch assembly 200 may be secured by the cover plate to the left side of the lower receiver 100. In alternative embodiments, the bolt catch assembly 200 may be secured to the right side of the lower receiver. Even more generally, the bolt catch assembly 200 may be secured to the lower receiver 100 such that it is constrained in all forms of motion with the exception of movement in one direction of motion, specifically it is only permitted to rotate about the longitudinal axis of the torsion bar 202.
As illustrated in FIG. 1, the magazine actuator arm 201 is located at or near the front of the pistol magazine 300, while the bolt catch 203 is located at or near the rear of the pistol magazine 300.
FIG. 3 shows a standard pistol magazine 300 for a handgun or pistol, such as a Glock magazine. The magazine follower 302 is shown, which travels linearly inside the magazine body 301. The magazine follower 302 has a hold-open tab 303.
FIG. 5 shows the improved bolt catch assembly 200 in two different operational states in a rifle. FIG. 5a shows the first position of bolt catch assembly 200, which occurs either when no pistol magazine is inserted or when the pistol magazine is inserted and the pistol magazine contains one or more rounds. FIG. 5b shows the second position of bolt catch assembly 200, when the pistol magazine is inserted but there are no rounds loaded in the magazine. FIGS. 6a and 6b show cross-sections of the first and second positions in FIGS. 5a and 5b, respectively. FIGS. 7-10 illustrate various perspective views of a carbine or rifle having an improved bolt catch assembly 200.
The operation of bolt catch assembly 200 with a standard pistol magazine 300 will now be described referring to the various figures.
When a standard pistol magazine 300 having one or more rounds is inserted into the rifle, the bolt catch assembly 200 will be in the first position or state of FIGS. 5a and 6a. As rounds are removed from the magazine 300 during operation, the magazine follower 302 travels upward toward the top of the magazine body 301 under spring pressure.
When the last round contained in the pistol magazine 300 is chambered by the carbine bolt 400, the magazine follower 302 shown in FIG. 3 travels linearly upward inside the magazine body 301 and the hold-open tab 303 of the magazine follower 302 will come into physical contact with the protrusion 205 shown on FIG. 2 on the magazine actuator arm 201.
The hold-open tab 303 of the pistol magazine 300 applies mechanical force to the protrusion 205 of the magazine actuator arm 201, which is then translated into the torsion bar 202 shown in FIG. 2 and the bolt catch 203. For example, the mechanical force applied to the magazine actuator arm 201 may result in the bolt catch assembly 200 rotating about the longitudinal axis of the torsion bar 202. The applied force causes the bolt catch 203 to move or rotate into the second position or state shown in FIGS. 5b and 6b. In FIGS. 5b and 6b, the hold-open tab 303 of the magazine follower 302 has engaged the protrusion 205 of the magazine actuator arm 201.
Once in the second position, as the bolt 400 of the carbine is returning from the rearward position, the bolt contact surface 206 of the bolt catch 203 engages the feed lip 401 of the bolt 400 shown in FIGS. 1 and 4. The engagement of the feed lip 401 by the bolt contact surface 206 of the bolt catch 203 prevents the bolt 400 of the carbine from returning to the forward position as shown in FIG. 1.
Thus, during firearm operation with the pistol magazine 300 inserted, when the last round contained in the pistol magazine 300 is chambered by the bolt 400, when the round is discharged from the carbine, the bolt hold catch assembly 200 will transition from the first state or position shown in FIGS. 5a and 6a to the second state or position shown in FIGS. 5b and 6b.
As noted above, the bolt catch assembly 200 may also include the optional over-travel arm 204 shown in FIGS. 2 and 6. In that configuration, when the bolt catch assembly 200 is in the position shown in FIG. 6a, there exists mechanical clearance between the over-travel arm 204 and the over-travel contact surface 104 that allows the bolt catch assembly 200 to rotate into the state shown in FIG. 6b, thus enabling the bolt catch 203 to engage the feed lip 401 of the bolt 400 as shown in FIG. 1. However, further rotation of bolt catch 203 will cause the over-travel arm 204 of the magazine actuator arm 201 to come into mechanical contact with the over-travel contact surface 104 on the lower receiver 100. If this occurs, over-travel contact surface 104 will physically limits the rotation of the bolt catch assembly 200 about the longitudinal axis of the torsion bar 202.
The bolt 400 of the carbine may be released by manual operation. The bolt catch assembly 200 may be rotated by depressing the lever 207 on the bolt catch 203 shown in FIGS. 2 and 5a, b. Depressing the lever 207 rotates the bolt catch assembly 200 to the configuration shown in FIGS. 5a and 6a by rotating the bolt catch 203 such that the feed lip 401 of the bolt 400 shown in FIG. 4 is disengaged from the bolt contact surface 206 of the bolt catch 203, thereby allowing the bolt 400 to return to the forward position.
Patent Application
20170241729
