I just saw the conversion question in the post below. I started looking at mag cylinders last year for an old model single-six. I called ruger and they said that only old models manufactured with a seriel number above 150000 could take a magnum cyclider and the gun would have to be returned to Ruger for set up.

Hope that helps anyone else, I'm glad I did it as it give me a dependable side arm for pig hunting with a muzzleloader in Georgia.

Oh, Ruger's service number is 603-865-2442.