Whichever one you can shoot the best. If the .357, a decent cast bullet like the old 162 grain # 358156 in an L or N frame revolver. Or load some of the nice old 170 grain #358429's if your gun can chamber them (load them in .38 +P casings for an N frame). In .45 Colt, well any good cast bullet will do.

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Vaya con Dios