Any reliability issues in single action?

Some side to side play in the cylinder is normal and necessary. I'm assuming your primer hits are in the center of the primer pocket, more or less.

What about end shake on the yoke, did you check for that? The two crowned sideplate screws can get switched and this can cause problems. The front sideplate screw is fit to the button on the yoke stem.

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Ret. LE, FA Instr, S&W Armorer