your not going to be able to use a x39 case for a 45 wild cat the od is to small. even a 308 win case would need to be reamed if possable at all. trust me i looked at a .44 on a x39 case it wont happen.
what if one used a x39 case and opend it up to take a .45? the case would not need a taper like on the .357 max. the base (x39) is close to a .45ACP, case cap for x39 is 33.45Gr, .45 ACP 27.67Gr. yes a .45 long colt would get the same type of load/ performace, but no semi auto and still could use x39 mags. might make a good brush gun. muttman