When you measure a cartridge in mm(like 9mm),exactly what part of the cartridge are you measuring?

Answer 1

The diameter of the projectile.

Answer 2

Depends. In the case of the .9x19mm the bore diameter is measured first, then the case length (the '19'). The theory is that a .355 bullet must emerge from a thirty-six caliber bore (.9mm translated to thirty-six caliber). Same with the .38 Special, the bore is thirty-eight and the bullet is something like .357 caliber. In the case of the old .38-40, the bullet diameter is measured and the bore is actually a forty caliber, which is why .40 S & W rounds can be shot through a .38-40; thoroughly confusing, isn't it!

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Answer 3

9mm is the diameter of the bullet of many loads used in Europe. The 9mm Parabellum or Luger, adopted by Germany in 1908, is the world standard for military cartridges by now. Even the USA switched to it in 1985. The 9mm Luger is also called 9X19mm to show both bullet diameter and cartridge case length. There is a 9X18mm Ultra and a Russian Makarov shell the same length. They are less powerful than the 9mm Luger.

Answer 4

Heck if I know. Maybe it's bullet diameter or groove diameter. Maybe it's bore diameter. Maybe it's a rough approximation and deliberately off a bit to avoid confusion with other cartridges of the same caliber, and maybe it's historically somewhat accurate but no longer applies to the current size after a prior change. Explain the 38-40 to me, with its .401" bullet and no history that I'm aware of that it's ever been loaded with 40 grains of any type powder, and perhaps it'll all come clear, but they really only give a very rough approximation of bore size until you learn the specifics. You just have to know that a 404 is a larger diameter than a 416.

Answer 5

The diameter of the projectile is the measurement. If it is in caliber.. it's the diameter in standard inches. For example, a .50 caliber is .5 of one inch.. or 1/2 and inch. .22 caliber is 22 one-hundredths of an inch.. and so on. If you see a rifle caliber, such as 22-250, the first number is the diameter (.22 inches). 30-06... is .30 of an inch. Typically, bullets created in millimeter are of foreign descent, and caliber listed bullets are American.

Answer 6

Well, in your case, you are measuring the bullet diameter. But when you see a cartridge like 7X57mm, 8X57mm, or 6.5X55mm, this is what it means. It means that the bullet diameter is 6.5mm in diameter, and the 55mm means that the brass casing is 55mm tall.

Answer 7

9mm is the nominal bullet diameter. .355 inches is the size in English measurement, and that equals 9.017mm.
25.4*bullet diameter in thousandths = mm size.
mm size /25.4 = size in thousandths of an inch.

Answer 8

the diameter at it's widest point

Answer 9

the bore size is in mm (metric),