What is the difference between center fire and rim fire ammunition

Factual Questions
1

Several questions:

What is the difference between center fire and rim fire? Does the hammer or firing pin actually fall on a different place on the round?

Why did the two types develop?

Is one superior to another for different purposes or calibers?

Any other useful info about these ammo types?

And: why would my local rifle range outlaw steel or bi metal jacketed ammo?

2

Yes, the firing pin hits the center of center-fire cartridges. That ignites the primer, which fires the powder.

In rimfire rounds, the hammer hits the edge of the cartridge.

Your range may not have a backstop that can handle steel-jacketed ammo well.

3
  • Yes, on rimfires, the hammer strikes on the rim, with centerfire it strikes in the center.
  • Because rimfire is cheaper to make, but has limitations in that the case has to be thin enough to crush properly on the rim, yet strong enough to not burst under the chamber pressures. Rimfires are all smaller calibers for this reason.
  • Rimfires are bad for autoloading guns because if a case jams while loading and doesn’t load completely, there is a -tiny- chance that the bolt riding forward could crush the rim enough to set off the case. Centerfires don’t have this problem. …There’s not much significant difference in accuracy, considering the rimfires’ limited range. The main reason rimfires were considered less accurate was due to their unjacketed lead bullets, which were less accurate. The 17-caliber rimfires (that use copper-jacketed bullets) have shown this to be the case. 17-caliver rimfire guns are typically considerably more accurate/consistent than their 22-caliber counterparts, even though the barrels are made to basically the same technical standards.
  • No, not really. 17HMR is fun if you don’t have the space to shoot larger rifle calibers, and it is more accurate than 22WMR.
  • Usually to avoid the danger of core fragmenting: because as the steel impacts metal or hard concrete, the steel penetrator cores shatter, throwing shrapnel at high speeds outwards, in any direction. Bullets made of only copper and lead won’t do this.
    ~
4

I have to take issue with a few things. Semiautomatic .22s are extremly commonplace and I’ve never seen one slamfire but I have seen several slamfires on centerfire weapons.

As for accuracy take a look at what is done in .22 benchrest with plain lead bullets. I own rifles in both .22LR and .17M2 and I can’t give an accuracy edge to either one.

5

Or the hammer hits the firing pin, which hits the edge of the cartridge (as with your center-fire example).

Agreed. If the backstop includes a deflector plate, this will likely get chewed up over time by jacketed rounds.
Another important difference between centerfire and rimfire rounds is that the former are usually reloadable, while the latter aren’t.

6

Modern ones are. But there have been rimfire cartridges up to .58 caliber, as noted here.

7

Thanks everyone, very helpful.