Sierra bullet makers say they have found no problem at all in shooting .311-.312 bullets thru .308" barrels & were in fact surprised that they shot as accurately as they did. I don't own a Mini-30 so I haven't kept up with the latest thing about a new bore diameter. Can anyone confirm that Ruger has actually begun installing .312" barrels on new model Min-30's? As to rechambering a factory Mini-30 barrel to a wildcat caliber goes I would approch this with a lot of caution. I would bet the farm that the reason Ruger never came out with the XG1 was because they found out the action wasn't strong enough for the 308 Winchester or 7.62 NATO round. And I would suggest that in their testing they had KaBooms because of the high chamber pressures & the large diameter bolt face. This is for harles, the reason you have the taper of the cartridge case is for ease of extraction something very improtant for a semi auto weapon but of no concern to a guy shooting a bolt action rifle unless he's hunting dangerous game. You'll find no military weapons chambered for Ackley Improved cartridges for this reason. I would caution anyone who reloads for the Mini to be very careful about how hot they are loading their rounds be well versed on how to read the signs of too hot a load. Remember that the most accurate rounds are usually found below maximum load.
Just my 2¢
Bushwack
Just my 2¢
Bushwack