I posted a question on the differences between 7.62x53 and 7.62x54 in Mosin Nagants in the milsurp section but figured I'd ask it here too in case anyone that knows doesn't check the milsurp section. Here's the thread:
http://northeastshooters.com/vbulletin/showthread.php?t=18802
http://northeastshooters.com/vbulletin/showthread.php?t=18802