5.56 vs. .223??

Keith, thanx for the info on the .223 brass. I'd never bothered to load for the .223 in the past, what with ammo being so cheap. Finally got a bolt-action, but so far I've only used civilian brass.

At any rate, I'm dubious that any ammo is loaded beyond 51,000 to 55,000 psi--and that shouldn't hurt any modern bolt-gun.

Comparing .308, however, I've found that civilian brass holds some three grains weight more powder than Argentine military...

Fifty years back, I used loading data book maxima for the '06 in GI brass. No signs of undue pressure, other than slight flattening of the primers. Learning, later, of the difference between GI and civilian brass, I came to believe the book info was just a bit conservative. :)

Art
 
Jeff,

No, according to the last line of the SAAMI piece posted just above your message, the CHAMBERS are different.

I really hate to say this, but I've fired a couple hundred rounds of surplus 5.56, American and Foreign, through a friend's Remington 700, and I've still got all my parts in the right places, as does the gun.

I wonder how much of a problem this really is, if at all?
 
Mike, based in part on what Keith said, if a GI chamber is a smidgen bigger, it still won't be more than a thousandth or two. All that would mean is that reloading scrounged-up GI brass in a bolt-gun would require full-length resizing. Seems like no big deal, to me.

Art
 
I looked at the SAAMI page that was mentioned, it was at least amusing. :) It states that you shouldn't attempt to fire 5.56, .222, or .30 Carbine in a rifle chambered for .223. I was OK until I read the .30 Carbine, what were they smoking when they assembled that list??? I don't try to fire .45ACP in my .32ACP guns either, because it won't fit! :D
 
Ah, but 30 Carbine rounds will fit in a .223 chamber. They are a little less than 2/100's inch smaller and have a similar rim. Now what won't fit is the .308 bullet in a .223 bore. That's the obvious reason for the caution. Don't leave both types of rounds lying around together during a shooting session.
 
I've been looking around and have not yet come up with a definitive answer. My feeling is, that the 5.56 and the .223 cartridge are indentical, the chamber marked 5.56mm is slightly larger than the commercial .223. I believe a problem occurs when buying an AR-15 barrel/upper from a parts distributor and they use .223 reamers instead of 5.56mm because the .223 reamers are more plentiful. Then many barreled uppers go out the door with tight chambers (for AR-15 semi or auto operation) because these companies don't want to invest more time and money in finishing these chambers correctly.


NOMLO BLEA
 
Clint, What's the difference between .308 Winchester & 7.62x51mm NATO?

Jerry Kuhnhausen, in his classic Shop Manual (available from Fulton Armory; see the M1 Rifle Parts & Accessories or M14 Rifle Parts and Accessories Pages under
Books) has published a somewhat controversial recommendation concerning .308 Winchester and 7.62x51mm NATO ammo, headspace & chambers. I broached the
subject with him some months ago. He had his plate full, so we decided to chat on this in the future. When we do I'll report the results of our conversation.

I completely agree with Jerry that if you have a chamber with headspace much in excess of 1.636 (say, 1.638, SAAMI field reject), you must use only U.S. or
NATO Mil Spec Ammo (always marked 7.62mm & with a cross enclosed by a circle) since the NATO mil spec calls for a far more "robust" brass case than often found
in commercial (read .308 Winchester) cartridges. It is precisely why Lake City brass is so highly sought. Lake City brass is Nato spec and reloadable (most NATO
is not reloadable, rather it is Berdan primed). Indeed, cheaper commercial ammo can fail at the 1.638 headspace (e.g., UMC) in an M14/M1 Garand. Many military
gas guns (e.g., M14 Rifles & M60 Machine guns) run wildly long headspace by commercial (SAAMI) standards (U.S. Military field reject limit for the M60 & M14 is
1.6455, nearly 16 thousandths beyond commercial (SAAMI) GO, & nearly 8 thousandths beyond commercial (SAAMI) field reject limit!).

I also agree that 1.631-1.632 is a near perfect headspace for an M14/M1A or M1 Garand chambered in .308 Winchester. But I think that it also near perfect for
7.62mm NATO!

I have measured many, many types/manufacturers of commercial and NATO ammo via cartridge "headspace" gauges as well as "in rifle" checks. If anything, I have
found various Nato ammo to be in much tighter headspace/chamber compliance than commercial ammo. Indeed, sometimes commercial ammo can not be
chambered "by hand" in an M14/M1A with, say, 1.631 headspace (bolt will not close completely by gentle hand manipulation on a stripped bolt, although it will close
& function when chambered by the force of the rifle's loading inertia), though I have never seen this with NATO spec ammo. I.e., if anything, NATO ammo seems to
hold at the minimum SAAMI cartridge headspace of 1.629-1.630, better than some commercial ammo!

So, why set a very long 1.636 headspace in an M14/M1A or M1 Garand? It probably is the conflict mentioned above. Military headspace gauges say one thing,
SAAMI headspace gauges say something else, as do the spec's/compliance covering ammo. In a court of law, who will prevail? I think Kuhnhausen gave all those
who do this work a safe way out. However, I believe it not in your, or your rifle's, best interest. Whether you have a NATO chambered barrel (M14/M1 Garand G.I.
".308 Win."/7.62mm NATO barrels all have NATO chambers), or a .308 Winchester chamber, keep the headspace within SAAMI limits (1.630 GO, 1.634 NO GO,
1.638 FIELD REJECT). This subject is a bit confusing, and for me difficult to explain in a one way conversation!

Clint McKee
http://www.fulton-armory.com/308.htm
 
OK, I give up dZ...

what does that say in English? IMO, my rifle is not an ex-military rifle so I probably don't have the wildly long headspace of a military M14 or M60 (dang!). So my contention that 308 or 7.62 will shoot in my M1A Springfield is right, right? ;) I hope it is, or all that milsurp I've shot has prolly done irreparable damage to my M1A and Colt AR 15s :o !!

Best regards, Herr Doktor!
 
I absolutely agree on the stupidity part, johnwill. But that wasn't the point, you said they wouldn't fit, and they do. They might even fire. We have had some not-so-stupid folks right here on TFL say they have loaded the wrong caliber round in their handgun. I don't see why it can't happen with a rifle.
 
It is my understanding that 5.56 and .223 are the same thing. However, the civilian chambers are a bit tighter than the military ones. But the ammo is the same.

This isn't quite true with the .308 and the 7.62 NATO, which have a slightly different spec.
 
No, they are not the same.

Look at the labeling of Winchester Q3131, its labled 5.56 mm. Try firing it in a Kimber. Better yet, try firing it in someone else's Kimber. It will cause sticking bolts, pierced primers and a whole host of other demons all because its loaded to higher pressure.

Its fine in most military rifles, at least ones made here.

Please see the SAAMI link, it mentions this non-interchangeability.

BTW, .223 is fine to shoot in rifles chambered for 5.56 but not the other way around.
 
While it's never happened to me, I can see getting 9mm mixed up with .40, since they really do look similar. However, I'll stand by my comment, anyone that can't tell the difference between .30 Carbine and .223 is an idiot! It really is just that simple.
 
Actually, I had a friend who once mixed up .222 with .223 rounds. Try telling those apart.

The .222's wouldn't fire ... just a bit shorter than a .223. But, it even took a gunsmith a little while to figure out that error. We all thought there was something wrong with the firing pin. ;)

Regards from AZ
 
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