Cartridge strip magazine for powder-actuated fastener setting tool

In combination with a magazine strip loaded with a cartridge, a powder-actuated fastener setting tool having a breech in whose inlet is nested a nose projecting from the magazine strip in which the cartridge is socketed, the cartridge when fired then producing a gas in the breech which expands to drive a fastener into a masonry body, and means to confine the expanding gas to the breech and thereby prevent it from escaping through a space between said nose and said inlet, said means comprising:

• A. a tool breech having an inlet formed by a frusto-conical upper entry section and an inwardly offset frusto-conical lower section, which forms an inlet step at a junction between the upper entry section and the lower entry section;
• and
• B. said magazine nose being formed of resilient plastic material having a lower frusto-conical section which when the nose is nested in the breech inlet then abuts and conforms to the lower section of the inlet to create a broad lower seal, and an outwardly offset upper frusto-conical section which forms a nose step at a junction between the lower frusto-conical section and the upper frusto-conical section and which then abuts and substantially conforms to the upper section of the inlet to create a broad upper seal which together with the lower seal acts to prevent the escape of the gas and wherein a zone is formed between the inlet step and the nose step in which gas leaking through the lower seal is depressurized therein.