Guys, way I see it, there's rules to make sure the playing field is level(ish).
And there's rules that mess with accuracy.
Nowadays, there are essentially two classes, plus Unlimited, where the bag gunners insist that they have an advantage because they can squeeze... Sigh...
Oughta turn it into 11.5, 13.5, big thing that kinda looks like a rifle, and whatever two or three guys can get to the bench without herniating themselves (much).
No caliber or case restrictions. Just weight and "has to look like a rifle" for the lower three, and "run whatever" for Unlimited. And make it -really- unlimited. Mag fed, semi, whatever, as long as it's safe, and brass doesn't go past the edge of the bench (which is likely the main reason for disallowing semi in the past, right?).