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Caliber Question

2K views 29 replies 18 participants last post by  yooper71 
#1 ·
I don't know anything about caliber. How is a caliber designation determined? Why doesn't the 9mm cartridge have a caliber designation like the 45 and 40 caliber round, etc.?
 
#2 ·
One is inches the other is millimeters. 9mm is .355 inches.
 
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#5 ·
Thanks for the good explanation. When you say bore measurement is that the diameter of the barrel bore? Does .45 mean .45 inches?
 
#6 ·
Bill, to best answer your question You would first need to put a point in front of that .45, or .40 caliber designation. Because they are fractions of an inch. .22, .32, .38, .357, etc..... The europeans measure theres in millimeters. 5.56mm, 6.5mm, 8mm, 9mm, 10mm, etc.... Shotguns are measured in bore gage,not caliber. [ except for .410 bore, notice the point in front] If you took 1 pound of pure lead and divided it into 12 equal parts, and formed one of those parts into a perfectly round ball, that would be the size of a 12 bore gage. It works the same for 10, 16, 20,28, and 32, gages etc.....

Does that help? DR
 
#9 ·
Bill, to best answer your question You would first need to put a point in front of that .45, or .40 caliber designation. Because they are fractions of an inch. .22, .32, .38, .357, etc..... The europeans measure theres in millimeters. 5.56mm, 6.5mm, 8mm, 9mm, 10mm, etc.... Shotguns are measured in bore gage,not caliber. [ except for .410 bore, notice the point in front] If you took 1 pound of pure lead and divided it into 12 equal parts, and formed one of those parts into a perfectly round ball, that would be the size of a 12 bore gage. It works the same for 10, 16, 20,28, and 32, gages etc.....


Does that help? DR

Yes that helps!! Thanks everyone for your great answers. Happy Thanksgiving to all!
 
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#18 ·
I look at it a different way. We put a man on the moon, but cant get a system of measurement that makes sense. Half the people in the US couldnt tell you the next size larger socket after an 11/16, but everyone knows that 13 comes after 12. I couldnt tell you how mant people ive met who have no idea how many yards are in a mile either, but 1000 meters in a kilometer isan easy conversion.

As far as caliber deisngations. There are so many different ways they come up with it. As people have pointed out, some are metric, or standard measurements, some of them are actually a measurement in the barrel, and not the bullet itself, and i think some even had do do with the grain weight of powder used at some point or something weird like that.
 
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