Inertia is the tendency of an object at rest to remain at rest, and it's the key to the Benelli system; When a gun is fired, all of the fixed parts immediately begin moving rearward; But if a part is not fixed, it initially stays put; Think of a handkerchief draped over the gun; If you fire, it will seem to move forward; Actually, it keeps its position while the rest of the gun moves to the rear; This is what happens to the bolt body when you fire a Benelli; it briefly holds its position as the rest of the gun starts to move backwards; The difference in motion between the bolt body and the rest of the gun compresses a short, very stiff inertia spring between the bolt body and bolt head; As the shot charge or slug leaves the barrel and rearward force on the gun diminishes, the spring vigorously rebounds, throwing the bolt body rearward with enough force to unlock the rotating bolt head, eject the spent shell and recock the hammer; The recoil spring then returns the bolt assembly forward, lifting and chambering the next shell and then locks the rotating bolt head into the barrel extension; Because the key to this operation is the predictable energy of the inertia spring, the Benelli system is adaptable to almost any sort of ammunition; About the only way to stop a Benelli from cycling is to put the butt against a brickwall; the shotgun must be free to move backward slightly to operate