Uh, excuse me. .45 caliber is .458 “ in diameter.
Thus, 6.8 caliber would be 69.2”.
Obviously they mean 6.8mm, as in 5.56 and 7.51........
I stand corrected. “22 cal” is really “.22 cal” which equals .22 inch but is simply referred to (verbally) as 22 caliber.
But the caliber is the inside diameter of the bore, land to land. Not the bullet diameter. So .45 caliber ammunition has a bullet that is slightly larger in diameter so it will form to the rifling of the barrel when fired.
“Thus, 6.8 caliber would be 69.2”
It would be kind of tough to carry spare ammunition. But it certainly be effective! :^)