A shooting buddy of mine broke the hammer part of his bullet puller and asked to use mine for his last few pulls. I invited him over and he noticed that I did not use the little aluminum collets in mine. When I told him that I used, and had been using. caliber specific cartridge holders from my reloading dies, he seemed shocked and surprised. Said he'd never heard of using them, and said I ought to let every reloader I know about this technique. So that's it, folks! No more chasing around finding the little rubber O rings or pieces of aluminum; just use the shell holder and save yourself the grief.