Abstract: A universally adjustable firearm stock is provided having adjustments for comb, cast, length of pull and butt pad height. The stock has an adapter (receiver model specific) to connect a frame to the receiver. An end of a mount passes through a slot through a frame seat. A cast piece is received within the seat and has a cast hole (center hole—no cast, offset hole—cast). The rearward extending end of the mount passes through the cast hole, wherein any offset in the cast hole results in an angular cast. The comb is vertically adjustable relative to the frame. Two rods are extendable relative to the frame to adjust the length of pull. A butt plate has two slots wherein the height of a butt pad relative to the rods is adjustable.

Abstract: A self-locking bolt assembly is provided having a short stroke allowing the assembly to be contained within the receiver. The assembly has a base plate, a recoil rod with a spring, a bolt body, a bolt and a locking mechanism. The bolt is internally (i.e. lockable onto itself) lockable when the bolt is in battery. The locking mechanism, for example, can be a roller bearing, a lever lock, a cam rotary lock or a roller. The locking mechanism engages to recoil rod and prevents rearward motion of the bolt. Blowback and reciprocation of the bolt are temporarily delayed after a shot is fired until after the bolt is unlocked. Rearward movement of the bolt body due to inertia causes the locking mechanism to be disengaged to unlock the bolt and to allow for reciprocation of the bolt.