The present invention relates generally to a drop bolt catch kit for establishing a last shot bolt hold open position. More specifically, the present invention teaches a combination bolt catch accessory fitting between upper and lower receiver assemblies associated with such as right or left handed AR-15 firearms, in combination with a uniquely configured magazine supported follower, and which provides full function bolt hold open/release capabilities. The combination catch assembly and follower is capable of functioning with rim fire conversion ammunition.
The incorporation of bolt catch mechanism, such as in use with AR-15/M-16 type firearms is known in the art, one purpose for which being the ability to hold open a bolt or slide of a firearm firing mechanism in order to inspect the chamber after all rounds supplied by a magazine have been discharged. One known example of an ammunition magazine with internally supported and upwardly spring biased follower body is disclosed in Westrom, U.S. Pat. No. 5,638,626 and which discloses a bolt catch actuator coupled to the follower. The actuator is biasingly seated within the follower and further exhibits an actuation finger which, upon aligning the follower with a notch indicative of a last shot being fired, projects the finger through the notch in order to contact the bolt catch and restrain the reciprocating bolt in the open position.
The present invention discloses a bolt catch assembly for use with a firearm including a receiver with an exposed receiving chamber and an underside engageable magazine. The assembly includes a bolt catch actuator housing supported in seating fashion relative to the receiving chamber and communicating with an attachable magazine. A catch actuator is supported in elevatable fashion relative to an end of the actuator housing. A follower component is upwardly and biasingly disposed within the magazine and which, upon contacting the catch actuator, displaces an associated bolt catch of the firearm in an upper and bolt restraining position.
The follower component exhibits a main body having a three dimensional shape and overall profile matching a cross sectional interior of the magazine and influenced in a generally upwardly biasing direction. An upper follower body extends at least a length of the main body and is supported in displacing fashion relative to the main body. The main body exhibits an upper configured and lengthwise extending channel, a partial superstructure supported within the channel, and a pair of side defined and upper end proximate slots.
Additional features include the upper follower body exhibiting an upper displaceable member which exhibits a generally elongated rectangular configuration seating within the lengthwise extending channel. The upper follower body also exhibits a lower ledge support and an upper angled/projecting catch actuator engaging portion.
A pair of seating pins extend through communicating locations with the slots, as well as like dimensional width apertures extending through the upper displaceable member. A spring is supported in an extending and seating fashion within a hidden location of the superstructure so that an opposite end is biased an abutting end surface of the upper follower body in a rearward induced direction. Other features include a modification of the actuator housing to incorporate an adjustment screw for adjusting a range of displacement of the upper displaceable member.
Reference will now be made to the attached drawings, when read in combination with the following detailed description, wherein like reference numerals refer to like parts throughout the several views, and in which:
Referring now to the several illustrations, the present invention teaches a bolt catch accessory and uniquely configured follower which can be installed between upper and lower receiver assemblies associated with any suitable firearm, but in one applicable variant to any of a related family of M-16 or AR-15 firearms. As further previously indicated, the bolt catch provides an improved and more secure assembly for achieving last shot bolt hold open position than is capable with prior art devices.
As will further be described in detail with reference to the several illustrations, the invention includes, as a first component, a bolt catch actuator housing supported in drop-in fashion within an upper exposed rim of a lower receiver housing chamber and which includes an end supported and elevatable bolt catch actuator for in turn engaging a conventional bolt catch component associated with a reciprocating bolt of the firearm. An associated follower component includes a main body with an upper configured and lengthwise extending channel, within which is seated a spring loaded and shifting upper component.
The bolt catch assembly (see as defined by actuator housing 10 and associated bolt catch actuator 12) is particularly configured for operating with rim fire ammunition (as opposed to center fire ammunition in which the firing pin strikes a primer cap at the center of a base of the cartridge). As is further known, rim fire ammunition includes a widened base rim which is essentially a widened percussion cap containing the desired priming compound, while the associated cartridge case itself contains the propellant powder and projectile (bullet).
Referring to
As further shown, the bolt catch actuator 12 fits into the actuator housing 10 as a packaged unit, and which in turn is placed within the open magazine well (again exposed chamber 16), such that the associated bolt catch 18 is captured or otherwise slaved to the catch actuator 12. In this fashion, the assembly is secured between the upper (not shown) and lower 14 receivers upon reassembly.
The bolt catch combines an integrally formed actuator catch engaging portion, again as shown at 18, in combination with a user accessible (e.g. thumb displacing) portion 20 such as for manually triggering the catch engaging portion. The catch actuator 12 further includes such as an open configured window, hidden from view in
The follower subassembly 24, in its uppermost displaced position within the attached magazine as depicted in the side cutaway of
Further variants of the invention contemplate use of the bolt catch actuator housing 10, without the associated bolt catch actuator 12. This can occur in situations where other (e.g. non rim fire) cartridges are employed and where it is desired to employ the actuator housing 10 alone in order to provide for a tighter fit with the upper engaging end of the magazine 18.
Referring again to
An upper configured and lengthwise extending channel is illustrated generally at 32 within an upper facing surface of the follower body 30, and which is defines a generally āUā shaped profile within a top of the main follower body 30. Additional features evident include a partial superstructure 34 supported within the follower channel proximate one end thereof, along with a pair of opposite side defined and upper end proximate slots 36 and 38.
The follower subassembly also includes an upper displaceable member 40 which exhibits a generally elongated rectangular configuration suitable for seating within the upper channel profile 32 of the lower follower body 30. The upper displaceable member 40 includes a length profile at least equal to and optionally greater to that of the lower body 30 and, at a rearward facing end, includes a lower ledge support 42 and an upper angled/projecting catch actuator engaging portion 44.
The configuration of the upper follower member 40 is further such that it is capable of being supported in lengthwise displaceable fashion within the channeled profile 32 of the lower body, in supported fashion upon the partial superstructure 34, and so that the arrangement and configuration of the ledge support 42 prevents the member 40 form pivoting or rocking during rear length displacement movement (see
Additional features include a pair of seating pins 46 and 48 which extend through the previously defined slots 36 and 38 as well as like dimensional width wise extending apertures 50 and 52 formed through the upper displaceable follower portion 40. A spring 54 is also provided and is supported in a seating fashion within a hidden location of the superstructure 34 so that an opposite end of the spring 54 biases an abutting end surface of the upper follower 40 in a rearward induced shifting direction (as further depicted by directional arrow 56).
In this fashion, and as is shown in
Referring to each of FIGS. 5 and 5A-5E, a series of perspective, plan and exploded views are successively depicted of a modification of bolt catch actuator housing 58 and which is largely similar to that previously depicted at 10 in
Additional features also depicted in the earlier variant 12 of the catch actuator again include a further pair of inwardly spaced legs or tabs 70 (
As is known, an associated bolt (not shown) is a mechanical part of the firearm which blocks a rear of the associated chamber during burning of the propellant. In semi-automatic firearms, such as is the case AR-15 type firearms, the bolt is caused to cycle back and forth during each cartridge discharge cycle, propelled by recoil/expanding gas (backwards) or spring recoil (forwards). Upon moving back, an elongated lug disposed upon a bottom of the reciprocating bolt strips the cartridge casing (also not shown) from the magazine and pushes it into the firearm chamber. Upon discharge, and once the spent shell casing case is clear of the chamber, an ejector component (also not shown but understood to also include an integral component of the bolt along with the firing pin), ejects the casing from the receiver and out of the firearm.
In operation, the interface between the follower assembly 24 and the bolt catch actuator 12 and housing 10 operate to provide a last shot bolt open condition, such as in conjunction with a rimfire style ammunition which varies the engagement structure established between the firearm configured bolt catch 18/20 and shell base.
Having described my invention, other and additional preferred embodiments will become apparent to those skilled in the art to which it pertains, and without deviating from the scope of the appended claims.
This application claims the benefit of U.S. Provisional Application 61/321,942 filed on Apr. 8, 2010.
Number | Date | Country | |
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61321942 | Apr 2010 | US |