TK Custom advertises that you still use regular ammunition if you wish too. The rimmed cartridges, like the 454 Casull and 45 Long Colt, have a rimmed lip that rests on the cylinder proper. They also make moon clips for rimmed cartridges. Also, if you wish to use a Speed Loader with your rimmed cartridges, that also works fine in a TK Custom altered cylinder. In end times, the ability to use more varieties of ammunition in the same revolver makes sense. I wish to have options without losing the qualities of the original set up. TK Custom has a made a cottage industry doing this.