Kind of an odd question I've been thinking about. Is there a reason why so many rounds are .30 cal / 7.62? I mean, as far as rounds developed here in the US, there's .30-06 (7.62x63), .30 carbine (7.62x33), .30-30, .308 (7.62x51), .300 Win Mag (7.62x67) and probably others, but it's not just...