223 Rem vs 5.56 Nato

[Kinsman]

This article cleared up the question for me....

http://www.humanevents.com/2011/02/15/223-remington-vs-556-nato-what-you-dont-know-could-hurt-you/

 

[Clark]

Re: 223 Rem vs 5.56 Nato

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The 5.56 case has thicker walls to handle higher pressures, meaning the interior volume of the case is smaller than that of a .223.</div></div>
That is true for 7.62x51mm / .308 Win, but that is not true for 5.56x45mm / .223 Rem.
Weigh the cases and see.
This is an often made mistake on the internet and often corrected.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased, creating the danger of a ruptured case or other cartridge/gun failure.</div></div>
As one seats the bullet longer and longer, the peak pressure drops, until the bullet is jammed into the lands, and the pressure goes up from the delay before the bullet moves.
This effect is simulated in Quickload by varying the start pressure. Off the lands, the start pressure for the bullet may be 2,000 psi, but jammed into the lands it may be 5,000 psi.
The feedback loop for knowing the approximation is right is the chronograph. If the chronograph data matches the Quickload velocity prediction, then start pressure modeling is likely being done correctly.
Using this process, we can see that the peak pressure only goes up a few thousand psi for being jammed into the lands.

The 5.56 is 62,366 psi.
The .223 is 55,000 psi.
But the case head will not get loose primer pockets in one firing until ~85,000 psi.
The case head will not fail, but the primer pocket will get very big at 95,000 psi.

What does it all mean?
The danger 5.56 ammo in a .223 is in the novice author's mind.

 

[1SMALLJOHNSON]

Re: 223 Rem vs 5.56 Nato

Clark,
No offense, but there are a few too many assumptions built into your statements.
The method of measuring pressures between the two DIFFERENT cartridges AND the leade geometry AND the case length specifications and tolerances prevents a 1-for-1 comparison.
It can NOT be said that there's X difference between the two cartridges. A computer model is only that; a model. It is entirely possible AND probable that one perfectly sufficient 5.56mm round could cause catastrophic injury to a person loading and firing that round in a .223 REM.
I mean no offense to you, rather I'm hoping to prevent potential problems for shooters. SAAMI lists a 5.56mm loaded and fired in a .223 REM under "Unsafe Arms and Ammunition Combinations" The public version ANSI will also tell you the same.

 

[Clark]

Re: 223 Rem vs 5.56 Nato

5.56 ammo is shot in.223 rifle a million times per day.
People who do this outdoors risk being struck by lightning.

 

[Ratwhiskers]

Re: 223 Rem vs 5.56 Nato

He said it wasn't shooting well, and sure enough it was spraynpray. Then l saw what he was stuffing into his rifle......

"Oh it's ok, l Mexican matched it so it's safe. And my pal uses it in his M4 straight pull, and says it should be good in my Tikka T3"

Well l told him to withdraw from the line, as Murphy wasn't invited to this shoot. But behind my back,12 rounds latter his G/F had it blow the extractor and stick the case in the chamber..... Oo.... She was a little pissed with him!!!

So l guess lightnin' does strike the foolish.
....