What Is the Difference Between Bullet Sizes?

Whether you’re a gun nut or a computer game addict, don’t worry you’re not alone, you’ll have commonly heard of the different types of bullet sizes. If the former, you can probably just move on but if you are curious we’d be glad to have you with us. What exactly are the differences between bullet sizes? Let’s take a quick look.

The following is intended as a basic overview of ammunition in general with some hand selected calibers in a bit more detail, it is not intended to be used as promotional material for buying or using firearms! That’s you told, enjoy.

[Image Source: Pixabay]

Housekeeping

First of all, we’ll go over some basics for those who don’t know the common terminology. This is not intended to be condescending to those who are firearm aficionados, so feel free to skip this bit. Still here? great. When we are talking about firearms you’ll have likely heard the term caliber. This simply means the internal diameter (bore) of the barrel that the bullet will be fired from.
Bullets are the bit at the end of the cartridge. The cartridge comprises of the bullet, propellant (usually powder), casing, primer etc. Here’s a handy diagram.

[Image Source: Range365]

Apart from caliber, ammunition also falls into two other categories, Rimfire, and Centerfire. This term describes the way the primer is distributed at the base of the cartridge. As the names suggest, Rimfire has the primer built into the rim at the base of the cartridge, whilst the other, well in the center. The former is generally a lot cheaper and tends to be restricted to smaller calibers.

Spent cartridges with an example of Rimfire on the left and Centrefire on the right.
[Image Source: Wikimedia Commons]

Bullet sizes do matter

When we refer to caliber, as we mentioned earlier, we are talking about the internal diameter of the barrel and by extension the bullet’s diameter. Technically speaking bullets are actually ever so slightly bigger than the barrel or bore. The bullet will squeeze down the barrel during firing which interestingly is the main reason the barrels get so hot during firing. Cool, well hot, right?
Anyway, we digress, bullet calibers can be a little confusing. They tend to be quoted in a mixture of imperial and metric sizes. Usually, hundredths, sometimes thousandths, of an inch or millimeters. So a .22 “round” is 22 hundredths of an inch etc.

They will also have another term you may see called “grain”. This describes the weight of the bullet, yes just the bullet. “Grain” is usually a very small number as around 7000 grains makes up 0.45 kgs, more or less. This is an old term used up to the Renaissance that referred to the weight of, yes you’ve guessed it, a grain, usually barley.

You may also be familiar with the term “stopping power”. This is somewhat vague and controversial, to say the least. Effectively it refers to the number of bullets you would theoretically need to “drop” a human. Clearly, if you hit them in the head, for example, it may only take one “round”. In most cases, you’d be aiming for the center of mass, chest or largest target. Bullets can have other traits that will cause damage to organs if not hit directly. There is also another term “hydrostatic shock” but we’ll leave that well alone here.
We’ll now focus a few commonly known or referred to calibers out there, there are many, many more.

9 mm Caliber

Yup of “Uzi” fame these are actually the same as .380 and .38 Special bullets. They differ, however, by the amount of gunpowder behind the projectile. These bullets tend to have very low recoil and are used in many guns. Compact 9mm guns can be used for concealed carry, for instance. They usually come in magazines of 15-17 rounds.
These tend to be the standard round for NATO forces and most police forces around the world. They tend to vary from 115-147 grains with variable stopping power.

.308 Caliber

The good ol’ “three-o-eight” inch is pretty much the same of the NATO “seven-six-two” mm round. These are popular hunting rifle rounds that have moderate recoil and high stopping power. They come in a range of 150 to 208 grains.

12 Gauge

Yup, these are very popular for shotguns. Seemingly contradictory, 20 gauge is smaller and 10 gauge is bigger than the 12 gauge. The reason for this apparent contradiction is that the term “gauge” refers to the amount of lead balls you can fit in the barrel. It derives from conventional imperial measurements of how many equal diameter balls you can make from 1 pound or 0.45 kgs of lead. You’re welcome.
These have variable recoil from moderate to high depending on the round itself. Shotgun ammunition is very versatile and can comprise of birdshot with lots of small balls. It could be buckshot with fewer but larger balls. Or it could be a slug which is simply a pure metal shot. Stopping power with these should be self-explanatory at short range.

0.50 Caliber

These are the mother of all bullets for handheld firearms and are not very common for civilian use. These are huge by comparison to other ammunition. Consequently, they have a very powerful recoil and incredible range. Often they have confirmed kills at ranges in excess of 2km. You seriously do not want to be hit by one of these. They tend to comprise of 660 grains of, well let’s face it, pure stopping power.

You might want to see this in action when fired from a Desert Eagle.
If you want to see more about other bullet sizes this is a great article.

So there you go. We hope we’ve given you some insight into the world of ammunition. We’ve covered some of the basics of projectile weapon ammunition and looked a little bit closer and some of the more commonly known bullet sizes. We’d be interested to hear your experiences and knowledge in this field. Also, if you’d like us to cover in more detail any aspects touched on in this article please also feel free to comment.