What Does Caliber Mean?

20190701PartCenterfire203x300Caliber refers to the internal diameter of a gun's barrel and consequently the diameter of the bullets that can be used by the gun. Bullet calibers can be a bit confusing, because some bullet diameters are measured in inches, while others are measured in millimeters. It's also important to understand that the bullet only refers to the actual projectile (see diagram to right).

If you look at the picture below, a .22 LR (.22 Long Rifle) is .223 inches in diameter, while the 9mm Luger round is 9 millimeters in diameter. If you knew nothing about guns or ammo, you might have assumed ammo referred to as "22 LR" would be bigger than one called "9 millimeter", but you can clearly see in the picture (from grandpappy.org) this is not the case. This is due to the difference in their units of measurement.


Important Note for Beginners: Always read the owner's manual for all firearms you own, and only use the recommend ammunition. Just because a cartridge fits into your magazine, does not mean it can or should be shot buy your firearm.

Why it's Important to Put Thought Into Your Handgun Caliber

The handgun caliber you choose will typically impact:

  • The cost of ammunition. As a general rule, the larger the bullet, the more expensive it is. However, other factors like how common the ammo is, its supply, and its demand will also affect its price. Below you can see a current estimation of the cost of ammo online by caliber. Keep in mind prices will vary over time.
Ammo Caliber                      Estimated Price Per Round
.22 LR (.22 Long Rifle) $0.05-$0.07
.32 ACP (.32 Auto) $0.38-$0.52
.380 ACP (.380 Auto) $0.29-$0.43
9mm (9mm Luger) $0.19-$0.24
.40 S&W $0.29-$0.38
.45 ACP (.45 Auto) $0.28-$0.34
.38 Special $0.32-$0.40
.357 Magnum (.357 MAG) $0.42-$0.68
.44 Magnum (.44 Mag) $0.54-$1.05
  • The Stopping Power of Your Gun & Ammo. While a variety of factors come into play when determining the stopping power of a gun and its ammo. The larger a bullet, the more likely it is to incapacitate an attacker.
  • The Recoil When Firing Your Gun. Though other factors play into recoil, a larger round typically equates to more recoil. Recoil strength affects accuracy because bullets that produce strong recoil will naturally move your aim further away from your target with each shot. Consequently, bullets with more recoil also require you to brace more in order to maintain accuracy.
  • The Time Between Shots. The larger recoil caused by larger bullets also means an increased time between shots if you want them to be accurate.
  • The Size of Your Gun. Larger diameter bullets require larger diameter barrels. They also require larger magazines in semi-automatic pistols, which gives you more to grip your hand around and potentially more to conceal.
  • The Amount of Ammo Your Gun Can Hold. For example, the standard magazine capacity of a Glock G17 handgun is 17 9mm bullets, compared to a Glock G21's magazine capacity of 13 .45 ACP bullets. These two pistols are nearly identical in size.

Determining The Best Pistol Caliber

The best pistol caliber has been endlessly debated on online firearms forums and at gun ranges alike. The truth is, there's really no one-size-fits-all answer. The best handgun caliber for you may be different from what's best for me.

With that said, the following should give you a general idea as to what's best for you.

Click here to continue reading... with thanks to our friends at GunPros


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