Why do bullets have such strange diameters? E.g. 7.62mm, 7.92mm, 5.56mm. How did they decide on these instead of something like 7.5mm, 8mm, or 6mm respectively? - Quora
Multi caliber weapon : r/Damnthatsinteresting
IMCOM Europe Region US Forces Sport Shooting Program
Why don't shotguns with rifled barrels shoot conventional bullets? If they ever existed, how did they compare to the same type of bullet fired from rifles? - Quora
7.92×57mm Mauser | Military Wiki | Fandom
8x57 JRS - www.balistique-joel-serre.fr
Fanzoj Sidelock double barrel rifle, in cal. 8x57IRS - Johann Fanzoj