Two .22 HP's I've fooled with actually shot better with the .224 dia. 55gr Sierra and the 55gr Speer than with the .227 Hornady's. 3031 did very well.
Going a little further with "groove to bullet fit", I have done extensive load development with the 7.62x53R Finn m-39 at 600 yards. Excellent results with .311 and .312 dia. projectiles shot in a bore that slugs .315. Which more or less confirmed an old article in Precision Shooter, done some years back. In a nutshell it was a compilation of tests of barrel wear longevity done by various governments using their own service rifles. IIRC, the '03 Springfield (.308/.308) showed a marked decrease in accuracy after 10K rounds, the '96 Moisin Nagant (.310/.314) had a roller coaster graph of decreasing accuracy to 14K rounds and then amazingly increasing accuracy up to 20K where the test was halted. This has nothing to do with the op, but I thought it was interesting.
