I'm always gratified when someone brings up something I've never, consciously, experienced before. And a caliber expressed as it's metric size, if that's how it was initially released, 9mm Parabellum, 9mm Kurz etc, is perfectly legitimate.
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Hey OP, are you going to tackle Pounders too? Brits are confusing as hell on cannons.......
Is a 17 pound gun as good as a 75mm?
Asking for a friend.....
Now SHOTGUN GAUGES are another thing that confuse people.
Most shotguns and ammo they fire are described in "gauges" which is NOT a caliber. It has nothing to do with saying how wide the bore is in inches, or fractions of an inch, or the decimal equivalent of that inch fraction.
A "gauge" in the gun world means how many pure lead balls of exact bore diameter would it take to add up to a pound of lead.
10 gauge (also called "10 bore") means each perfectly-fitting lead ball would weigh 1/10 of a pound.
20 gauge would use lead balls that weigh half as much, so it takes 20 of them (not 10) to make a pound.
.410 isn't a gauge, it's a caliber. Just like you'd use for describing the bore of a rifle or pistol in English units based on the inch.
But for "GAUGES" you don't use a decimal. They're all more than one.
A " .20 gauge" gun, (that really is 1/5 of one gauge) would have a bore so wide that one single lead ball that fits down its barrel would weigh 5 lbs. That would be a cannon with about a 2-inch bore, I think.
So it's just "twenty gauge." Not "point-twenty gauge" or "period-twenty gauge."