Abstract: A recoil reducer for a shoulder firearm including a main piston that moves axially in a cylinder disposed in a cavity in the firearm stock to intersect the butt of the firearm, the main piston being connected via a piston rod to a plate that supports a shoulder pad spaced rearwardly of the butt such that major portions of the firearm can move rearwardly when the firearm is discharged. The main piston has an aperture formed therethrough, said aperture having a frusto-conical portion and a threaded portion to receive corresponding threaded and frusto-conical portions of the piston rod.