TheGunSource.com is proud to bring you the most extensive Rifle Caliber Guide on the internet. If you can shoot it out of a rifle then we’ve written about it here!
Welcome to your guide to rifle calibers where you’ll learn to select the right cartridges for your hunting and shooting needs. Hopefully hunting season is right around the corner in your neck of the woods!
Now this article is going to begin by covering some basic information about rifle calibers and cartridges for the sake of any readers who may be new to rifle shooting or are planning to take up hunting for the first time. The rest of the guide will describe the most popular rifle calibers, some of their history, and key specifications.
First, let’s clarify some of the confusion around cartridge caliber designations so you’ll sound like you know what you’re talking about. Standard naming convention tends to describe rifles and ammunition by their ‘caliber’. The term caliber refers to the nominal bore diameter of a rifle in inches or millimeters. It also refers to the diameter of the bullet projectile, or sometimes the cartridge case.
The modern cartridge (or round) consists of the bullet, case, propellant (gunpowder), rim, and primer. A common misconception is to describe a round of ammunition as a ‘bullet’. Just know that a bullet attaches to the case, which are both part of the entire manufactured cartridge. A ‘centerfire’ cartridge is one with a replaceable primer located in the center of the case head. Most cartridges are centerfire, except for some of the smallest which are rimfire.
Ammunition cartridges are usually named after their bullet caliber (diameter). Caliber is measured with either imperial or metric designations depending on where the cartridge was manufactured. For example, a .223 Remington refers to the imperial measurement of a specific cartridge with a bullet diameter of roughly .22 inches. The metric equivalent is 5.56 millimeters, and its specific cartridge is designated as the 5.56x45mm NATO (the ‘45mm’ refers to the length of the case).
Caliber designations don’t always describe bullet sizes, or even exact measurements. For example, the bullet diameter of a .38 Special is actually .357 inches, like the .357 Magnum (the .38 describes the case diameter). A 9mm bullet (0.35 inches) is the same size as a .380 ACP. A 6mm rifle (0.23 inches) fires the same round as a .243 caliber rifle. Sometimes cases can be wider than bullets. It’s definitely going to help to get some rifle shooting tips.
Variations in nomenclature can be due to cartridges being modified or repurposed for certain firearms while keeping the designation of their parent cases. Often the difference between cartridge rounds with equivalent projectile sizes, but different names, is to distinguish between varying powder charges, chamber pressure, and case lengths.
The way firearms and projectiles are categorized by caliber is honestly quite confusing and it’s not the point of this article to dig deeper into the matter. However, there are a few important metrics that are associated with rifle calibers that you should consider: bullet mass (grains), muzzle velocity (feet per second), muzzle energy (foot-pound), and recoil energy (foot-pound). Keep in mind that bullets with different mass can be used in the same cartridge which will affect its ballistic performance (only one weight is listed in this guide). You’ll also need to consider which shooting targets are most appropriate for the type of caliber, and you’re probably going to need a good rifle scope to match. So let’s move on to the list of the most popular rifle calibers!
