The Model 63 is a 22 LR 6-shot stainless revolver. Maybe it was a 6-shot S&W Model 651 22 WMR which is the identical revolver to the S&W Model 63 except for a slightly longer cylinder and the resulting shorter forcing cone.
I have each with 4" barrels. I know that they made the earlier Model 651 with a 2" barrel but I don't know if a newer model with a 2" barrel now exists in S&W's line-up. IIRC, the newer Model 63's have an 8-shot cylinder but not sure about a current production Model 651.
I'm sure if you look around on the web that you can find more informatino.