Abstract: An auto sear for a firearm having a lower receiver with a trigger, disconnector and hammer, and an upper receiver with a reciprocating bolt carrier group. The sear includes a body pivotally mounted within the lower receiver rearwardly of the trigger, disconnector and hammer. The body includes a forward-most planar shaped portion in which are configured each of lower and upper trip engagement location. Upon the hammer initially striking the firing pin, the bolt carrier subsequently displaces rearwardly following cartridge discharge in order to rotate the hammer downwardly into contact with the lower trip engaging location. Upon a return forward displacement of the bolt carrier, an underside ledge thereof contacts the upper trip engaging location in order to pivot the lower engaging location out of contact with the hammer, permitting the same to rotate back into striking contact with the firing pin.

Abstract: A bolt hold open (BHOA) catch assembly configured for operating with rimfire ammunition for use with a firearm including a receiver with an exposed receiving chamber. A BHOA housing is supported upon the lower receiver in communication with a receiver chamber in communication with a bolt assembly. A catch is supported in elevatable fashion relative to an end of the actuator housing and an end most and downward extending structural portion of the elevatable catch is capable of being manipulated by an externally configured and toggled bolt catch so that an inner pivoting end portion thereof engages the structural portion to raise the BHOA supported catch into contact with a forwardly traveling bolt, such as upon release of a previously retracted charging handle. The BHOA catch can alternatively be actuated upwardly by a suitably configured follower associated with an attachable and cartridge holding magazine, this again following a last shot hold open protocol.

Abstract: The present invention teaches an insert locking mechanism incorporated into a sub caliber action device, installable within an upper receiver of an AR-15 type firearm, and which interfaces with an upper receiver mounted forward assist for use with such as .22 caliber ammunition and in order to eliminate movement or play of the chamber insert adaptor associated with the substituted sub caliber action. The mechanism includes a generally cylindrical shaped body supported upon the action and exhibiting a plurality of radially projecting and circumferentially extending lugs which are configured to mate and seat within a plurality of grooves circumferentially arrayed within a barrel defined in the upper receiver.

Abstract: A bolt catch assembly configured for operating with rimfire ammunition for use with a firearm including a receiver with an exposed receiving chamber. 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 bolt catch component and integrally formed actuator catch engaging portion is slaved to the catch actuator in order to be displaced in response to elevating motion exerted upon the catch actuator, such as by a follower component biasingly disposed within the magazine. The follower, in its uppermost displaced position within the attached magazine, engages a tab associated with the catch actuator which extends over a communicating interior of the bolt catch actuator housing in communicating alignment with the exposed receiving chamber.

Abstract: 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.

Abstract: A retrofit chamber adaptor associated with a substitute action assembly incorporated into a firearm for permitting the substitution of an original designated cartridge for a substitute cartridge. An elongated body is incorporated into a barrel accessible location of the firearm and supporting a bolt in reciprocating fashion. The chamber adaptor is mounted to forward end of the body in communication with the reciprocating bolt and exhibits a modified diameter aperture extending therethrough and corresponding to an incremental modification in diameter associated with the substitute cartridge. Additional features include a receiver plate incorporated into the body and exhibiting a generally lengthwise extending notched or keyed interior established between generally parallel extending sides with identified and interiorly notched locations for seating in reciprocating fashion therebetween the reciprocating bolt.

Abstract: The present invention teaches an insert locking mechanism incorporated into a sub caliber action device, installable within an upper receiver of an AR-15 type firearm, and which interfaces with an upper receiver mounted forward assist for use with such as .22 caliber ammunition and in order to eliminate movement or play of the chamber insert adaptor associated with the substituted sub caliber action. The mechanism includes a generally cylindrical shaped body supported upon the action and exhibiting a plurality of radially projecting and circumferentially extending lugs which are configured to mate and seat within a plurality of grooves circumferentially arrayed within a barrel defined in the upper receiver.

Abstract: 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.

Abstract: A bolt catch assembly configured for operating with rimfire ammunition for use with a firearm including a receiver with an exposed receiving chamber. 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 bolt catch component and integrally formed actuator catch engaging portion is slaved to the catch actuator in order to be displaced in response to elevating motion exerted upon the catch actuator, such as by a follower component biasingly disposed within the magazine. The follower, in its uppermost displaced position within the attached magazine, engages a tab associated with the catch actuator which extends over a communicating interior of the bolt catch actuator housing in communicating alignment with the exposed receiving chamber.