Colombian Mauser Problem

[madsenmac]

I have a 50's era sporterized Colombian Mauser that, as far as I can tell was re-chambered from 7mm Mauser to .30-06. The rifle shoots reasonably well and is fairly accurate. The issue is that it seems to be "belling" the bottom of the cases. There is approximately a .010" difference between the base and the belled portion. The belled portion is approximately .311" from the headstamp. I'm guessing the issue is with the way the chamber was cut. I'm also guessing that the only fix is to re-barrel the rifle. What do you all think?

[Delkal]

You cannot rechamber a 7mm Mauser (or 8mm) to 30-06 since the bullet size is different. Many Columbian Mausers were originally made in 30-06 so it likely left the factory that way. Are there any caliber markings on the barrel?

There is always some expansion from the rim / lowest portion of the base to the area slightly above it but 0.010 seems excessive. You can always see a slight line and a bell ~0.3 inches up but I think it should be 0.002 max. You should get it looked at by a gunsmith.