What is the difference between mm and caliber?

When it comes to guns and ammo, “mm” and “caliber” are two terms that are often used interchangeably. However, there is a difference between the two.

In firearms terminology, caliber refers to the diameter of the barrel bore, while mm refers to the cartridge size. For example, a 9 mm firearm has a barrel bore that is 9 mm in diameter, while a .45 ACP cartridge has a diameter of approximately 11.43 mm.

So what does this mean for you as a shooter? In general, smaller calibers produce less recoil and are easier to control than larger calibers. Larger calibers tend to be more powerful and can inflict more damage on targets than smaller calibers.

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The caliber of a gun is the diameter of the barrel, in millimeters. The length of the barrel also affects the velocity of the bullet, so a shorter barrel will have a smaller caliber than a longer barrel. For example, my revolver has a .357 magnum caliber, but its barrel is only 2 inches long. A rifle would typically have a larger caliber than a revolver because rifles have longer barrels.

The mm measurement is used for both calibers and other measurements related to guns and ammo. For example, bullet diameter is measured in millimeters (e.g., 9mm), as is cartridge length (e.g., 50mm).

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When it comes to guns and ammo, “caliber” is the term used to describe the diameter of the bullet, while “mm” refers to the size of the barrel. In other words, caliber is a measure of how wide the bullet is, while mm is a measure of how large the gun’s barrel is.

For example, a 9mm gun has a barrel that’s 9 millimeters in diameter, while a .45 caliber gun has a barrel that’s 45 millimeters in diameter. And since larger calibers equal larger bullets, they also tend to cause more damage when they hit their target.

In firearms terminology, caliber is the approximate internal diameter of the barrel, in hundredths or sometimes thousandths of an inch.

The term is also used to describe the length (or “bore”) of the barrel, in inches.

For shotguns, it is usually expressed in terms of gauge (U.S.), with higher numbers meaning a smaller diameter barrel.

Caliber is related to the length of the cartridge case, with shorter cases enabling higher pressures and larger calibers.

A firearm’s caliber can also be expressed in millimeters (mm), as a fractional measurement of its bore diameter. For some types of ammunition, such as blank and flare cartridges, the caliber is listed as a measure of the weight of the powder charge.

When it comes to firearms, “caliber” is used to specifically describe the diameter of the rifled barrel, while “mm” is a general term that refers to both the caliber and the length of the barrel. As a rule of thumb, a gun with a larger caliber will produce more damage than one with a smaller caliber.
For example, a 9mm bullet is typically shorter and wider than a .22LR bullet. And because it has more surface area in contact with the target, the 9mm round will cause greater damage upon impact than the .22LR round. However, other factors come into play when determining how effective a particular cartridge will be, such as velocity, weight, and design.

Caliber is the diameter of the bullet, while mm is the length of the barrel. For example, a 9mm handgun has a barrel that is 9mm in diameter, while a .22 caliber rifle has a barrel that is 22mm in diameter.