Don't tell the Britishicon NRA, you'll give them a headache!

Nothing comes to mind immediately as to hard data, but several factors could come into play w/ O/S bullets- bearing length, jacket type, jacket thickness, throat geometry, possibly core construction. If only a thousandth or two over, I'm thinking the throat configuration could play a most important part.

If an Arisakaicon can push a 0.308" projectile out of a 6.5mm bore w/o letting go...