Quote Originally Posted by Rapidnick
Surprisingly enough the way it was done by one gunshop owner I knew, was to place the muzzle hard up against a piece of material like rubberised matting and dry fire. Apparently, the pressure against the rubber is enough to slow the piston down at the end of its travel as if a pellet was in the breech.
sounds about as sensible as using your finger in the end of the barrel