引用:
原帖由 jacky2038 於 2019-5-6 12:04 發表 
why they are called 5.56 and 7.62 ?
bullet diameter?
but it seems they are not about diameter
how about .223 .308 , how they measure to these numbers
thanks !
5.56 and 7.62 are in mm, they are bullet diameters
.223 an .308 refers to 0.223 inches and 0.308 inches, if may take reference of these cailbers after you convert them into mm.
something like this:
In case of doubt, google is your goodest friend
