T-star is correct about the folks wanting to fit the cylinder. It's not rocket science, but it does take some careful figuring before you pick up your tools. I have 7.5" 45 Blackhawk with cylinders in 45 Colt, 45 ACP, and 45 Win Mag that I've set up this way. It's a good shooter, but aside from the unusual factor, there's not much real reason to do it. Still fun though. - dan