Okay, Snakeman, what is the parent case for the 375 round?? If the bullet company made a brand new case just to give them a monopoly and screw the customer, you could be S.O.L.
It wouldn't hurt, however, to look through your reloading manual and see if there isn't something with the same RIM diameter (give or take a couple mils...) and pressure rating as the round you are trying to make. There are a lot more steps to this, and c.r.butler will be HAPPY
to help you out with the rest.
Okay, the same case head belongs to the 307 Winchester, the 308 Marlin express, and the .356 Winchester.