Abstract: An explosively-actuated fastener setting tool comprises a barrel which can be moved forwardly after firing in order to open a breach for loading of a fresh charge. Forwards movement of the barrel also enables a spring-loaded stop to pivot through a slot in the barrel and engage the head of a firing piston to thereby reset the piston in the barrel. In the normal, breach-closed position of the barrel, the stop is fully retracted from the barrel. The configuration permits increased opening movement of the barrel. Further stops between the barrel and tool body engage in a forward position of the barrel to prevent the rear end of the barrel slot from impacting against the pivotal stop.

Abstract: A noise reducer for a powder actuated fastening tool comprises a barrel including inner and outer cylindrical walls which are radially spaced to define a gas expansion chamber between them. The chamber is adapted to receive combustion gases through ports or passages in the inner wall, and the gases may be exhausted from the chamber in any appropriate manner, preferably at a location adjacent the front end of the tool. The outer wall of the barrel can thus be made to slidingly fit within the tool receiver, while porting of the expansion chamber can be such as to induce a favorable flow pattern to the combustion gases passing therethrough.