As suggested, the Single Six is too small. The body of 25/20 is larger in diameter than the 32 H&R. Bowen, Linebaugh, and Reeder use a blank cyclinder from Bowen that's $300 at gunsmiths' cost and it only fits the late model frames (44/45 frame). This piece needs to be built on the pre-73, "old" style frame (a true 357 frame). I guess you could take and turn that cyclinder down and face it off until it fits that frame, but we are talking lots of machine hours. I've had the same idea for some time because I remember when Christie's Gun Works in Sacramento( I have a reward if anyone can find them) used to sell extra cyclinders for Colt SAA's. I have one their 45 ACP's for my Colt, rough machined on the outside, but shoots great. They used to list 22 Hornet, 25/20 and the likes. Can't get it out of my head. Like the last fellow, I got one of the T/C barrels. Great fun with either open sights or red dot. Death and destruction on jackrabbits. Full rifle speed with factory loads in a 10" barrel. Average 1386fps for Win jacket factories. Runs the same out of my CL. BUT, (memory just kicked in) in the 60's I had seen where Frank DeHaas and others had the chambers in the cyclinder RELINED and rechambered to smaller calibers. Then you could either reline or replace the barrel... Nothing cheap about us!