First, put an empty resized .38 case in and see if it rotates okay. If it does, then the problem is with the ammo. If it hangs up, then try to notice at what point it is rubbing against the recoil shield or loading gate. That would be a good start. The 1860 R-M's that are chambered in .38 are actually the same frame and cylinder as the '51 R-M, with the Army style barrel and grip.