Nice Gun! I bought one from a Pawn Shop for $160. 3 screw Super Single Six. I asked the clerk about the 2 loose Ruger cylinders on the carpeted shelf. He showed them to me, both were serial numbered to the Gun in my hand and were in .22 MAG.
One was fluted and one was non-fluted, I took the non-fluted one and tried in in the gun. It worked perfect and indexed properly. I thought it would be easy to tell which cylinder was in the Gun by this method and kept it. He didn't charge me any more for the extra cylinder, thought it was with the deal. Fine says I, and off I went . Great shooting gun with both cylinders. Mfg in 1970, it will be with me till I croak.