Beeman 10616GP Sportsman Combo Gas Ram 177 Pellet 1rd, Black, Fixed Synthetic Stock, Fiber Optic Sights, 4x32mm ScopeThe advanced technology of the gas ram system uses compressed gas in a sealed, self contained unit that is designed to replace the mainspring in a conventional air rifle. The air rifles cock like any other barrel cocking airgun, but the single cocking stroke compresses a cylinder of gas instead of a mainspring. When the trigger is pulled, the compressed gas expands and drives the piston forward. The main advantage in a gas ram air rifle and a real