No. The .22 mag bullet (and case) is larger in diameter as well as length than a .22 LR.

Ruger made the "Single Six" with two interchangable cylinders, one for .22 LR and one for .22 mag, but the BARREL was sized for the .22mag. The barrel can be a little bigger than it needs to be, but not a little smaller.

If you were to do such a conversion on a S&W, you'd have to do the same as Ruger, I believe - start with a .22 mag gun, and then get a .22 LR cylinder.

Also beware that bad things can happen if you chamber a .22 LR in a .22 mag cylinder. Since the brass is smaller than the cylinder I.D., it can split when fired. Not good.

I've often wished that S&W would make a convertible .22 J-frame alloy snubbie with 2 cylinders, however. How cool would that be!