Thread: Cartridge name vs actual size

Commercialism has a lot to do with naming as well. The Yanks tradionally didn't warm to metric names and in fact going back a bit there are a couple of cartridges that failed to take off in USA because they were given metric names instead of Imperial sizing names.
Have a read of this - https://www.thoughtco.com/how-ammuni...-named-1926781

And as Danger Mouse points out where the measurement is taken has influenced naming as well.
The classics are 303British versus 308Winchester with the 303B firing the larger diameter projectile.