I found this interesting from an old posting on another site:
"No fully automatic weapons may be used of course.
Other than that, the type of rifle is not limited.
The number of rounds the gun holds has not been limited, due to the fact currently legal shotguns are not limited and can hold just as many rounds.
Bolt action, single shot, lever action and semi auto’s are all legal, provided they fire ONLY LEGAL cartridges.(ie, a RIFLE which fires both a .410(legal) AND a 45/70(NOT legal) would NOT be legal to use)
Other cartridges are also legal, just as long as they meet the cartridge dimensions listed above."
I wonder if this is legit. I know many who will agrue that it is legal to use a 45/70 rifle as long as you are using 47/70 shorts which have been trimmed to the legal length. I personally understood the rule to be that if the rifle could fire an illegal round then it was not ok to use. Maybe I am misunderstanding since I am in the minority.