Hammer-drive powder-actuated tool

A hammer-drive powder-actuated tool adapted for activating ignition of a rimfire cartridge, the rimfire cartridge having a rear end and an annular primer disposed at the rear end of the rimfire cartridge, said tool comprising:

• a hollow tool body extending along a front-to-rear direction;
• and
• a firing device disposed within a rear end portion of said tool body and including:
• a pin holder having a through hole extending along the front-to-rear direction,
• a firing pin movable forwardly and rearwardly relative to said pin holder and having a firing end portion that is disposed at a front end thereof and that extends into said through hold in said pin holder, and a central axis adapted to be aligned with that of said rimfire cartridge along the front-to-rear direction, a front end of said firing end portion of said firing pin having a diameter adapted to be larger than an inner diameter of the annular primer and smaller than an outer diameter of the annular primer, and
• wherein said through hole in said pin holder has a front hole section, said front hole section having a front distal end, a rear distal end, and a diameter that reduces gradually from said front distal end to said rear distal end so that said front hole section has a minimum diameter at said rear distal end, the minimum diameter of said front hole section being adapted to be smaller than the minimum diameter of the rear end of the rimfire cartridge.