The invention provides an improved gun for firing a projectile comprising a grip, a receiver, a projection on either the grip or receiver and a retainer fixedly attached to the other, so that the projection and retainer selectively engage each other, retaining the grip and receiver in a fixed relationship. The apparatus provides a safety retainer and a safety projection, whereby the safety retainer and safety projection engage one another when the hammer is in the ready position, maintaining the grip and receiver in the fixed relationship. A safety member is provided preventing the retainer from disengaging the projection when the hammer is in the ready position, and blocking the hammer from moving into the ready position when the retainer is not in the first position and the hammer is not in the ready position. The invention provides a process for making a receiver for firing a projectile.