Abstract: The invention concerns improvements in a hammer-activated, powder-actuated drive tool comprising an elongated tubular housing, a tubular piston guide telescopically received extending from the front end of the housing, a piston telescopically movable within the piston guide, a chamber secured to the rear end of the piston guide for mounting a power load therein, and an activating assembly mounted on the tubular housing rearwardly of the chamber and comprising an elongate member slidably mounted relative to the housing and having a rear end extending outwardly of the housing at the rear end thereof and a forward end extending within the housing for contact with a power load mounted within the chamber. One improvement comprises providing the tubular housing with an internal bushing for slidably mounting the elongate activating member formed as a one-piece integrally molded member which experiences substantially no mechanical loading due to the activation of the power load.