I did a search and did not see any info about this so here is some info. I was at the gun show in San Diego this past weekend and bought a gizmo named "Convert-a-Pell" and basically it is an adapter that fits in the barrel with sealing o-rings and some special made cases that use primers and those little .177 lead pellets. I bought it so my wife can practice with her Detective Special and not get tired since she has arthritis pretty bad. It works like magic and we can shoot in the garage at a target box about 15 feet away with nearly no noise. I got 1000 pellets and 1000 primers for about $10 so that is a lot of target practice for very little $$$$. There are adapters for most all revolvers of all calibers and the owner can make special orders too.