In guns, whats caliber?

Question

When there is a .45 Caliber round, how does it differ from a 9mm round? Why do they specify caliber on some bullets and mm on others?

So the difference is region specific? If we were to use a bullet thats equivalent to a .45 caliber bullet in millimeters how much would that be?

Thanks a lot quasimodo1957 and d! It cleared things up.

Answer 1

this refers to the size of the round. .45ACP is a bullet .45 inches in diameter in a shorter casing. 7.62X39 is a rifle round (known just from experience). When the number is given as two number with an x, the first is the diameter of the bullet or shell, the second is the overall lenght of the round with the bullet in the the casing. To recap, bullet diameters are given in calibers and millimeters, 1 caliber = 1 inch. the 7.62 x 39 round is 7.62 mm diameter bullet and 39mm long when unfired.

Basically mm were used by countries that used the metric system and for new rounds made in the US, by new i mean a new design. Since the .45 caliber has been around for well over a hundred years, they kept the name the same instead of converting .45 in to mm. So the difference is only region specific in this sense. for general info, 25.4 mm is approx 1 in. 7.62 mm is .30 caliber. these can be used to convert between caliber and mm if desired, just use proportions [1in/7.62mm]=[xin/ymm] substitute the desired conversion (either .45 caliber or 9mm) into the appropriate place and solve for the other variable.

Answer 2

Caliber To Mm Conversion

Answer 3

This Site Might Help You.

RE:
In guns, whats caliber?
When there is a .45 Caliber round, how does it differ from a 9mm round? Why do they specify caliber on some bullets and mm on others?

Answer 4

Depends on where their developed the 9X19 mm aka 9mm Lugar aka 9mm Parabellum (or for war)was developed in Germany.

.45 Caliber was developed here. There are to many configurations to go through from the .45 ACP to the .45-70 government to list

But the .45 ACP is 45 hundreths of an inch with the ball ammo has a bullet that weighs 230 grains versus the 9X19 the ammo is around 180 grains. The 9 MM is a faster round but the .45 has more stopping power. It's an unending debate which is better, but I trust my life that has protect generations of Americans more than the 9mm.

Answer 5

Caliber is the size of the bullet in fractions of an inch (generally speaking). A .45 caliber bullet is .45 inches in diameter while a .22 bullet is .22 inches in diameter. Rounds marked in mm are generally from weapons developed first in Europe or Asia but still denote the diameter of the bullet.

Answer 6

45 caliber is a much larger (and much slower moving) round than the 9mm. The millimeter rounds are NATO/European while caliber is primarily United States. The military in the US now uses 5.56mm for hand held troop weapons, the issue to each infantry soldier unless assigned a specific crew weapon. The pistols issued were once .45caliber and are now 9mm Barettas.

This is a brief answer and not terribly detailed but hopefully it gives you alittle insight into this.

Answer 7

They both represent the diameter of the inside of the barrel. The first one uses the English system (in inches) and the other uses metric. So the difference is the size of the barrel and the round that goes into it. A .45 caliber is about 11.4 mm.

Answer 8

The size of the round