A 6.8 caliber would be .068 inches in diameter. Fixed it for you. :)
You "fixed" it wrong.
6.8 caliber would be 6.8 inches. The same as .50 caliber is roughly 1/2 an inch.
However, it is more likely "6.8" = 6.8 MILLIMETERS which would equal ~.267 or ~.268 caliber.
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........