I have 2 rifles designed to shoot .311 - .314" bullets. One is a P14, that has the 303 EPPS chamber. This barrel slugs just over .313"
My 1910 Ross has been rebarrelled, so it is a .311 groove diameter pipe. The Epps has the original 1916 vintage barrel, but still will
shoot consistently around 1¼ - 1½ moa at 100 yards. It's preferred bullet is that Sierra Pro-Hunter 180, chased by IMR 4320 or VV N540.
The Ross is another story. It shoots most bullets I have tried so far under moa. [From the Speer 150 (.311") right up through Steve Redgwell's
200 grain FB (.3135") It really likes Reloder 15 or Ramshot Big Game, but shoots well with several powders around that burning rate.
I really enjoy shooting my 303's. The Epps has taken several deer, and has performed admirably. The Ross will hunt this fall. Dave.