Modified bolt assembly and firing mechanism for an MG 34 Mauser rifle

A semi-automatic firearm comprising:

• a bolt assembly which operates from a closed bolt comprising a bolt housing, a bolt head, locking lugs positioned on a forward end of said bolt housing, adjacent said bolt bead, an aperture formed in a face of said bolt head, a pair of rollers positioned on opposite sides of said bolt head, a firing pin positioned within said bolt housing, a firing pin string positioned about said firing pin, a firing pin adapter positioned about said firing pin and protruding out of said bolt housing, and a cocking nut affixed to said firing pin;
• a receiver comprising a groove milled out of each side of said receiver for cooperation with said bolt assembly, and a groove milled into the bottom of said receiver for cooperation with said bolt assembly;
• a firing mechanism comprising a trigger, a trigger spring positioned adjacent said trigger, a disconnector pivotally attached to said trigger, a sear arm which engages said bolt assembly, said sear arm having a positive engagement cam, a sear arm spring positioned upon a rearward portion of said sear arm, and a rocker positioned within a pocket formed within said sear arm;
• a barrel.