My ancient set of RCBS carbide 38-357 dies (I can't remember exactly when I bought them) came with a a spacer that you would just put under an adjusted 38 length die, (Do they even do that any more?) and it worked O.K. for the magnum length brass. Not perfect, but close, depending upon case length. (Does anybody hate trimming pistol brass like I do?) PITA, but...if you desire consistent crimps, you gotta!