What Does the Caliber of a Gun Mean?
In the world of firearms, the term "caliber" is often thrown around, but what does it actually mean? In a nutshell, the caliber of a gun refers to the diameter of the barrel (or bore) of a firearm, measured in fractions of an inch or mm. However, there is more to it than that. In this article, we will delve into the nuances of caliber, exploring the different types, their relationships, and what they signify for gun enthusiasts and laypeople alike.
How is Caliber Measured?
Caliber measurement is a straightforward process that determines the diameter of the inner barrel of a firearm in inches or millimeters (mm). The most commonly used unit of measurement in the United States is decimal inches, while in European countries, millimeters or metric units are more typically used.
Here’s the formula to calculate the barrel caliber (1:40; 1:50 rule):
- Decimal Fraction: Divide the barrel inches by 40 (12-gauge, 44-caliber) or by 50 (22mm, 5.45mm)
- Non-Decimal Fraction: Barrel inches divided by 42 (20-gauge)
For example:
- For a 12-gauge, the barrel diameter is usually around 0.71 inches (18.7 mm). To calculate it, divide 0.71 by 40 for a decimal fraction or use the non-decimal approach: 0.71 ÷ 42 gives you approximately 0.17 inches.
Bore vs. Gauge Size
Now, let’s clarify the difference between bore and gauge size to avoid confusion:
- Bore size refers to the diameter of the barrel (caliber).
- Gauge size is a rating system for shotgun barrels measuring the weight of a small lead ball that can safely be fired from the same barrel.
Types of Calibers
Handguns, rifles, shotguns, and other small arms have distinct caliber arrangements. Here’s a simple breakdown:
- Revolver Calibers:
- Small-Caliber:.22-,.25-,.380-caliber (easier to handle, less energy)
- Medium-Caliber:.38 Cal (.38 Special,.40 S&W),.9mm Luger
- Large-Caliber:.44 Magnum,.45 ACP, 10mm
- Rifle Calibers:
- Service Rifle: 5.56mm NATO,.308 Winchester, 5.45mm
- Hunting Rifle: 7.62mm(.308),.30-’06 Springfield,.260 Remington
- Survival/E Pistolcalibarle:.22 Hornady Magnum,.223 caliber
- Shotgun Calibers (Gauge):
- 10-gauge → 12-gauge, 16-gauge and smaller
- Some shotguns use a modified gauge system (e.g., 20-gauge, 28-gauge)
Caliber, Velocity, and Energy
