Bullet Terminology Guide

So we’ve covered bullet caliber and you’ve picked out the size you wanted. Now you’ve gone to the store and looked at the ammo and….oh crud there’s lots more stuff on here than just the caliber! 115 grain, 150 grain, +P, FMJ, ZOMG!

Well, it’s time for part two of the basic bullet info: Advanced Terminology!

Let’s dive right into it.

The first thing you’re probably going to see is the “Grain”. When I first started, I had assumed that this was referring to the amount of powder. Actually a grain is a unit of weight equaling 1/7000 of a pound. It’s a pretty precise measurement and the bullet manufacturers use that to make sure the weight of the bullets is consistent. So a 115 grain bullet is equal to 0.0164285714 pounds. The higher the grain, the heavier the bullet. The heavier the bullet, the more force it’s going to have when it hits the target.

The next thing you’re going to see is maybe a “+P”. This means that the bullet is “overpressure ammunition”. In basic terms, it means that they pack a lot more powder into the cartridge than what is supposed to be there. Think of it as attaching a Nitrous Oxide system on to your car. It’s going to boost the performance of the bullet but it’s not something you’re going to want to use every day at the range. What I do is I buy a magazine for my guns that’s specifically for the protection bullets and it’s only loaded with +P ammo. I then have another magazine (or 5) for use at the range. When I get home, I clean the gun then slap the +P magazine into it for storage/carry.

There are only a few bullets that use the +P loading. Here are the most common ones and their performance:

(Table courtesy of Wikipedia)

The last one is the type of bullet itself. A long time ago, a bullet was just a ball of lead. These days, they’ve found that the bullets work better if they wrap the soft lead in another, harder metal. This is usually referred to as the “jacket”. You can still get unjacketed bullets, but with the way rifling is in the gun, I wouldn’t recommend it as it can get gummed up in the barrel. That’s a bad thing.

The main designations are:

Full Metal Jacket (FMJ)

This is more than just an awesome Stanley Kubrick movie, this means that all sides are jacketed in a hard metal (usually copper) but the bottom is left open. If the bullet was 100% surrounded by metal, it would be a “total metal jacket”. This ammo is usually what you’ll wind up with when you buy ammo at the range. It’s also usually the cheapest version of the ammo. I wouldn’t recommend this for defense ammo, however, as the bullets won’t expand when they hit a target. Usually they’ll just pass right through a person and that isn’t as good of a thing as it seems.

Hollow Point

This is a situation where the name is a near perfect description of the bullet. In this case the tip of the bullet is hollowed out. This causes a bullet to expand its diameter when it hits the target, often times to about 1.5 times its size. This leads to more damage to the target. Frankly, if you’re going to have a gun for protection, this is the bullet type you want to load it with.

Soft Point

This is a semi-jacketed bullet with the tip unjacketed exposing the lead, usually with a blunt tip These aren’t very common because hollow point bullets have better expansion and penetration.

When you’re looking for self defense ammo, I would recommend +P hollow points with the highest grain possible.

If you’re just going to putz around at the range: light, FMJ and cheap is the way to go (unless your gun is really picky about ammo weight. Check your owner’s manual to be sure)

I would avoid lead-only bullets at all cost, unless you’re playing around with muzzleloaders and such.