Don't know, but as a past owner of two older S&W J frame .22 mags (650 & 651), I'll share a little info. It is a strange sensation to shoot a J frame and have the same amount of noise and muzzle blast as you would experience with a .38 Special, but have no recoil. Also, while you might sometimes get by with shooting a .22LR handgun without ear protection (if necessary), don't do it with a .22 magnum!