Chamber insert lock installed within an AR-15/16 barrel extension for locating and reducing movement of an associated sub caliber action

摘要

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.