US Patent 7587851 Receiver gasket

A gasket designed to fit into the bottom of the lower receiver of an M16 and AR style rifle. The gasket assists in preventing debris and blown primers from inhibiting the firing motion of the trigger of the rifle. The gasket surrounds a portion of the trigger within the lower receiver without impeding the movement of the trigger. The gasket lies flat in the bottom of the lower receiver and is retained in place by the installed trigger and trigger spring.