Actually caliber is the diameter of the bore,There are many 308 caliber rifle CARTRIDGES.308 Win,30-06,30-30 yada yada yada.
True but there is a reason for a little ambiguity.
I only have multiple rifles in interesting and useful calibers .......
.277. ......... .284 . ....... .308 (caliber not cartridge) .
I answered the OP ? Correctly and yet protected the family 'jewels'. <G>