Abstract: A power amplifier for a low velocity piston driven powder actuated tool. The power amplifier accommodating a stacked arrangement of a pin or stud and a second stage power load including a power pill. Such power amplifier in one form is provided as a replacement for the lower tool end piece. The power amplifier is sufficiently strong to withstand ignition of the power pill. The lower end of the piston that is driven through the tool, in accordance with the invention, is provided with a shearing tip. A first stage power load is ignited to drive the piston. The piston propels the shearing tip against the power pill to ignite the power pill and in concert with the force of the piston, drives the pin into the work piece with the relayed forces rivalling that of a high velocity powder actuated tool. Also included is the feature for exhausting the power load generated gases from the barrel upon recoil of the piston.