I picked up a custom 1888 commission Mauser that had not been converted over from the old .318" J bore to the later .323" 8mm Mauser. (I've slugged the barrel to confirm it), I'm having trouble locating .318" bullets, and I was wondering if .321" cast lead bullets (170 grain) would be too much for it. I plan on keeping the velocities down to around 2,000 fps since that's what those early loads are rated at.