.223 vs 5.56

[zabbo]

I know a few people that say they are the same thing. For the most part, as far as I have found that is pretty much the truth, but there a couple subtle differences I have read. The shoulder on, I think the 5.56 cartridge is steeper and the pressure developed in 5.56 is considerably higher. That said, as I understand it, firing .223 in a 5.56 rifle is not a problem, but 5.56 in a rifle chambered .223 can be? Any further words of wisdom??

[Dean2]

Originally Posted by zabbo

I know a few people that say they are the same thing. For the most part, as far as I have found that is pretty much the truth, but there a couple subtle differences I have read. The shoulder on, I think the 5.56 cartridge is steeper and the pressure developed in 5.56 is considerably higher. That said, as I understand it, firing .223 in a 5.56 rifle is not a problem, but 5.56 in a rifle chambered .223 can be? Any further words of wisdom??

The 5.56 is designed to be shot out of Semi auto rifles. The pressure difference is not enough to affect a bolt 223. 223 55,000psi, 5.56 58,000 psi. I have shot lots of Milsurp 5.56 in my bolt guns and never had any pressure signs. Military brass tends to be thicker and heavier than civilian brass and handles the increased pressure just fine.

[elkhunter11]

The only issue, is if you use loads developed in commercial cases, in the thicker military cases, it can drive pressures up.

[FishOutOfWater]

223 Wylde... A chamber for both cartridges.

[fps plus]

The external dimenensions of the brass casing is the same. Headspace is the same . The military chamber is the same except for the throat , where it is designed to shoot the heavier bullets and therefore the throat and leade are longer in the military . The issue becomes the possibility of having pressure levels rise when shooting military case in standard 223 rem chamber.

[catnthehat]

Originally Posted by FishOutOfWater

223 Wylde... A chamber for both cartridges.

The great Bill Wylde never did collect any royalties on his reamer specs, too bad, he would have made a pile of cash!
There are many rifles and barrels with the Wylde chamber being made,and it is simply fantastic for driving those long 75 to 95 grain bullets out to 1K!
Cat

[kayaker]

SAAMI MAP is 55kpsi

CIP MAP for .223 is 62kpsi which is the same as NATO spec for 5.56x45

[antmai]

I throw a bolt and have never seen or had a concern.
As stated, i believe it only to be an issue in semi guns and even then, only ones that are specifically .223 chambered.

[catnthehat]

Originally Posted by antmai

I throw a bolt and have never seen or had a concern.
As stated, i believe it only to be an issue in semi guns and even then, only ones that are specifically .223 chambered.

The original .223 Remington chambers and the 5.56 chambers are different , as and there are subtle differences in the specs.
Fiting .5.56 Nato ammo a bolt action .223 Remington rifle these days , although the pressures developed will be higher, I doubt very much that a difference will be noticed however except maybe in accuracy .
Most companies are running a Wylde type chamber in their rifles these days , because the .233 Remington was not originally designed to shoot the very long, heavy bullets we are launching today, not even the bullets that were originally designed for shooting in the .
5.56 Nato.
Some manufacturers like Bill Ruger scoffed at the notion that their rfles should not fire alternate ammo , but their chambers ibwoukd wager are not built not to the original .223 SAAMI specs.
As a matter of fact ,many .223 Remington match rifles are twisted almost twice as fast as the originals were!
Cat