Bennelli's patent expired in 2006, thus the Browning copy of it's recoil operated system. As I understand it, the bolt head and carrier are spring loaded to each other. Once turned to the locked position the cam slot is now straight and allows the carrier to move forward and compress the spring. When fired, the carrier essentially stays stationary while the rest of the gun recoils rearward, compressing the spring. As it bottoms out, the spring snaps the carrier rearward and imparts enough momentum to it to cycle the action.
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