CalvinHey now! That's a carryover from "heeled" bullets like the .22lr in which the bullet diameter was flush with the case…which was and is .38 of an inch!
.30 measures lands diameter, .308 groove diameter
The real whackadoodle nomenclature are those lazzeroni magnums. A millimeter designation for groove diameter, not land diameter…why call something a .25 cal, nice quarter inch mark, when we can call it a 6.37 blackbird or whatever the heck it is. Makes me wonder if that guys a closet Canadian!
As a rural Canadian, I feel the confusion all too much of what the heck is going on. Are we or are we not metric!!!!????
I load about 0.0000015 Stone of RL 22 behind a 6.8mm to get about 22 cubic furlongs per fortnight of energy,,,, and diesel peaked at $1,96 CDN per litre.