I read several times the idea that the .22 Magnum cylinder would work in the M-617so I had one fitted to mine (six shot) and am very pleased, shoots just fine and the accuracy is as good or better with the mag cylinder installed. Another post questioned whether S&W would perform the mag cylinder fitting/installation but they would not because of the liabilities involved. My reason for having this done was because I was unable to find a M-648 for which I looked a year or more. Just to be clear the cylinder installed in my revolver is a six shot, not a ten, no experience with the ten.

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Sam
S&WHF 333 S&WCA 2198