Patent ID: 7575139

Claim:
An explosive discharge actuated tool using a loaded cartridge for driving fasteners, comprising: a barrel ( 16 ) having a bore ( 26 ) with a leading end ( 29 ) and a trailing end ( 27 ), the bore length being shorter than the barrel length, the bore ( 26 ) having an opening only at a firing chamber funnel ( 80 ) at the trailing end ( 27 ) of the bore and at a muzzle aperture ( 33 ) at the leading end ( 29 ) of the bore, the firing chamber funnel ( 30 ) covering the loaded cartridge in the firing chamber ( 44 ) prior to the cartridge exploding thereby directing the resulting force down the bore ( 26 ); a muzzle nose piece ( 28 ) having a predetermined length with a leading and trailing end, and a muzzle bore ( 31 ), extending from the trailing to leading end of the nose piece that is smaller in diameter than the diameter of the barrel bore ( 26 ), the trailing end of the muzzle nose piece ( 28 ) being attached to the forward end ( 22 ) of the barrel ( 16 ); a piston ( 82 ) with a leading end and a trailing end ( 83 ), sized to fit the barrel bore ( 26 ) and having a length that is less than the length of the barrel bore ( 26 ); a piston rod ( 84 ) having a leading and trailing end attached to the leading end of the piston ( 82 ) by the trailing end of the piston rod ( 84 ), the piston rod having a diameter sized to fit the muzzle bore ( 31 ) and a length selected to provide a predetermined distance between the leading end of the piston rod ( 84 ) and the leading end of the muzzle nose piece ( 28 ), when the piston ( 82 ) is in firing position; and a spacer-fastener ( 118 ) having a length equal to the predetermined distance between the leading end of the piston rod ( 84 ) and the leading end of the muzzle nose piece ( 28 ), and a diameter sized to fit into the muzzle bore ( 31 ); whereby inserting the spacer-fastener ( 118 ) into the muzzle bore ( 31 ), after the tool has discharged, so that the spacer-fastener ( 118 ) does not extend beyond the leading end of the muzzle nose piece ( 28 ), moves the piston rod ( 84 ) and piston ( 82 ) into firing position with the trailing end of the piston ( 82 ) at the trailing end ( 83 ) of the barrel bore ( 26 ) and the trailing end of the spacer-fastener ( 118 ) and leading end of the piston rod ( 84 ) being in physical contact, before firing.