US Patent 8056276 Backlash vibration structure for toy rifle

A backlash vibration structure for toy rifle (air soft rifle, BB-rifle) formed of a receiver extension, a weight, a reaction spring and a buttcap spacer is disclosed. The weight has a front extension inserted through the lower receiver of the toy riffle and connected to the rear end of the piston spring at the rear side of the piston so that the component parts of the backlash vibration structure doe not touch the piston during movement of the piston. An adjustment knob is provided at the buttcap spacer for adjustment of the reaction spring to adjust the level of the backlash vibration.