gumaro

Same old deal as the 7.62x51 NATO an .308

gumaro

Here is some info,


".223 Remington vs. 5.56x45--Chambering and Throat Considerations
Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.

Should you be worried about shooting 5.56x45 milspec ammo in a .223 Remington? The answer really depends on your chamber. 5.56 x45 ammo is intended for chambers with longer throats. If you shoot hot 5.56x45 ammo in short-throated SAAMI-spec chambers you can encounter pressure issues. The new long-throated 'Wylde' chamber allows safe use of military ammo. Wylde chambers are quite common in Rock River guns. Other manufacturers, such as Fulton Armory, offer modified "match chambers" with extended throats that allow safe use of 5.56x45 ammo in .223 Remington rifles. For a complete discussion of the .223 Rem vs. 5.56x45 question, read this Tech Notice from Winchester, and this GunZone Commentary by Dean Speir. Without belaboring the point, we'll repeat the official SAAMI position: "Chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber. SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer."

read at
223 Rem + 223 AI Cartridge Guide

jnfphd

Chambers are not the same, with the 5.56 having more headspace and a longer throat for variations in ammo. Watch out on putting military ammo in a .223 as high pressure ammo could be a problem. As Gumaro said, the Wylde chamber is a popular compromise. Good reference is Ammo Oracle:

The AR15.com Ammo Oracle

On the brass, I've always heard that military is thicker and has less case capacity. May really depend on the age of the brass. According to the guys at 6mmbr.com, who are smarter than me (though that's not saying much), most modern brass has about the same capacity. Gumaro's got the link I'm familiar with.

On Sig210:

Very nice pistol, though I prefer the 226 sport.

Best of luck.

Jim

sgtD

I own two firearms in this caliber range. One is an SAR-3 AK chambered and marked for 5.56 NATO, the other is a MINI-14 that is marked as chambered for the .223, however the owner's manual clearly states that it is safe to fire 5.56 NATO in the rifle. Thus, I fire either one in both and have for some time with no troubles.

As to other types of firearms, I can't say. I just know either one works in mine.

As to the brass question, military brass is definately thiker than most commercial brass. Thus the inside dimensions are reduced. It's not as noticeable with the 5.56, but put a military 30-06 or .308 case in the press to resize and then do a commercial case and you can feel the difference. It is also visibly apparent when looking at the case on end.

That is not to say that all commercial cases are thinner, some may not be, but most are in my limited experiece.

I have some 5.56 cases and some .223 cases downstairs that are made by the same manufacturer. I bet the 5.56 cases are heavier. I'll have to weigh them and see.

Take care.

__________________
When you've got 'em by the balls, their hearts & minds will follow. Semper Fi.

Thanis

Not really. The opposite.

.308 Win (civilian) vs 7.62x51mm NATO (military). Safe to fire military round out of civilian firearm, but not civilian round out of military firearm.

vs

.223 Rem. (civilian). vs 5.56x45mm NATO (military). Safe to fire civilian round out of military firearm, but not military round out of civilian firearm.

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S&W 642 (no-lock) with .38 Spl +P 135 GR Gold GDHP
Glock G31 & G33 with .357 Sig 125 GR. SXT Winchester Ranger

gumaro

When I said same old deal, what I meant was that it is the same argument about it being 2 different rounds that some people interchange without knowing if it will be safe. I should of clarified this, sorry.