I like those grips.Where did you get them from?
"J" frames?
S&W revolvers (since WWII) came in four frame sizes, from smallest to largest they were:
J - Model 34, 36, 63, 651, etc.
K - Model 10, 12, 19, 66, etc.
L - Model 586, 686, 696, etc.
N - Model 25, 27, 28, 629, etc.