The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 09-14-2005, 06:04 PM
Lynwood Slim Lynwood Slim is offline
Guest
 
Join Date: Nov 2003
What is the difference between center fire and rim fire ammunition

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?
Reply With Quote
Advertisements  
  #2  
Old 09-14-2005, 06:16 PM
Bricker Bricker is online now
And Full Contact Origami
SDSAB
 
Join Date: Dec 1999
Location: Northern Virginia
Posts: 43,478
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.
Reply With Quote
  #3  
Old 09-14-2005, 06:17 PM
DougC DougC is offline
Guest
 
Join Date: Mar 1999
Quote:
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?
- Yes, on rimfires, the hammer strikes on the rim, with centerfire it strikes in the center.

Quote:
Why did the two types develop?
- 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.

Quote:
Is one superior to another for different purposes or calibers?
- 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.

Quote:
Any other useful info about these ammo types?
- 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.

Quote:
And: why would my local rifle range outlaw steel or bi metal jacketed ammo?
- 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.
~
Reply With Quote
  #4  
Old 09-14-2005, 06:48 PM
Padeye Padeye is offline
Member
 
Join Date: Nov 1999
Location: Phoenix, AZ, US
Posts: 7,672
Quote:
Originally Posted by DougC
- 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.
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.
Reply With Quote
  #5  
Old 09-14-2005, 07:11 PM
Xema Xema is offline
Guest
 
Join Date: Mar 2002
Quote:
Originally Posted by Bricker
In rimfire rounds, the hammer hits the edge of the cartridge..
Or the hammer hits the firing pin, which hits the edge of the cartridge (as with your center-fire example).

Quote:
Your range may not have a backstop that can handle steel-jacketed ammo well.
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.
Reply With Quote
  #6  
Old 09-14-2005, 07:17 PM
Xema Xema is offline
Guest
 
Join Date: Mar 2002
Quote:
Originally Posted by DougC
Rimfires are all smaller calibers ...
Modern ones are. But there have been rimfire cartridges up to .58 caliber, as noted here.
Reply With Quote
  #7  
Old 09-15-2005, 12:12 AM
Lynwood Slim Lynwood Slim is offline
Guest
 
Join Date: Nov 2003
Thanks everyone, very helpful.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:40 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.