There are two styles of bullet cartridges you’re going to encounter out there: rimfire and centerfire. What’s the difference? Well, the rimfire is set off from the rim and the centerfire is set off from the center. Well, that was an easy guide. Next!
What? You wanted more? Alright, but remember: you asked for it...
In the grand scheme of things, all bullets work the same: You have a casing, a primer, gunpower and a bullet. The firing pin of the gun hits the primer which creates a tiny explosion. That tiny explosion sets off the gunpowder which forces the bullet itself forward and out of your gun. The difference between the rimfire and the centerfire is in where that primer is.
Never having gone out of style, but never in the forefront either is the rimfire. It was originally patented in 1831 (but has been around before that) and, oddly enough, hasn’t changed much. The entire inside edge of the cartridge is a big, flattened primer. The advantage to this design is that it is cheap to manufacture. The downside? Well, the nature of the casing means it’s pretty much limited to small calibers. You have to have some relatively flimsy brass to handle the rimfire set up. As a result, the powder necessary to propel a larger bullet would blow the brass apart. There are some large caliber rimfires available but you have to look hard for them and they’re antiques and very expensive. The other downside is that once the cartridge is fired, it is permanently deformed and can’t be reloaded. Most of all, there’s also a bit of a reliability issue with rimfires. That’s the main reason that hardly anyone will recommend a rimfire pistol or rifle to be used for personal defense. Having shot a bunch of .22 LR, I can honestly say I would never bet my life on them.
Why would anyone use them? Well, you can get well over 500 rounds for about $12-$15. They’re great for varmint hunting and plinking. I own a .22LR pistol and I can say it’s one of the most fun guns in my collection to shoot. The most common, and pretty much only calibers you’ll find in rimfire are .22 and .17 caliber bullets.
It’s safe to say that the most widely used cartridge style today is the centerfire. When you think of a bullet, this is what you’re thinking of. Brass casing with the little nub in the center of one side. That nub is the primer. The firing pin hits that primer and, well, you know the rest. They came about just a few years after the rimfire was patented. Unlike the rimfire, the empty casings can be reused over and over again. Just pop out the spent primer, press a new one in, refill, crimp and go. That’s another article, however.
With centerfire, you can have much bigger rounds (Magnum .500 anyone?). They’re far more reliable and there’s a lot more variety. They’re also more expensive.
Both have their uses and both are a lot of fun. It’s a safe bet, however, that you’re going to deal with centerfire cartridges a lot more.
Image Used under Creative Commons License from Richard Elzey.