Mac,

While your at it, maybe you could help me out on a "project" I want to have done. I'll be getting a set of Valmet 375 Win Big Bore barrels and would like to re-chamber them to 375 FM. The problem doesn't appear to be in wall thickness or the sort. I have a set of '06 that were re-chambered to 30 Super and they work just fine.

My concern is the rim thickness... .063 in the Win and .055 in the 375. Do you have any suggestions as to what I might get into here, and what else I might consider? I was thinking of using a 348Win case, but the base is somewhat larger, and it isn't a commercialy produced round like the 375 FM??? Also, I want to drive 300 gr bullets at 375FM velocities without high pressures.

Can I build up the extrector rims a bit and cheat with the headspace a bit...is this all too spooky...?