The HKS 36 “works” with .38 S&W in my pre-war Regulation Police. It’s ever so slightly off center due to the thumbpiece, but I can load with it. I wouldn’t try any tactical drills, but it’s faster than individually loading those stubby little cartridges.
Good shootin’,
Doug
The J frame 32 HKS works both in my 1903 I frame and a post war 32 RP. As with the 38 RP mentioned by CapnB, the cylinder release is somewhat in the way on the early prewar 32. The post war RP has a flat latch but the Magna stocks make for a tight fit. If you are just looking for a convient way to carry extra rounds try the plastic strip loaders.