Call Me Tim
Dramacrat
Yes. Diameter but in mass we use grains. Same with powder.we do use metric a lot when measuring our bullets.
Generally people have no idea.
You really want to cook your noodle?
A .38 is a .357 (.36 caliber) with a different powder charge, and is also a 9mm (9.07mm)
I still get confused by that one. Had to look that one up to make sure.