Calibers or cartridges?
Caliber is .24 and larger.
Cartridge is .24 cal and larger, 1.16-3" case length (rifle spec, private land).
There are so many cartridges that are legal.......production, obsolete, foreign, wildcat......too many to list.
With respect to OP...I'm not sure what part of "bullet diameter 6mm/0.243" or larger, with a case length between 1.16 and 3" is so difficult to understand.