[I_Hunt_Liberals]

Okay, aren't the .223 and 5.56 nato the same round?
And, aren't the 7.62x51nato and .308 the same round as well?
Can somebody clear this up for me??

Thanks

[jlwatts3]

Yes, in fact I think they are.

[greg700]

Actually, the .223 and the 5.56 Nato are not the same round, though it is possible to shoot one in a rifle chambered for the other.

There are some minor differences. I am not particularly knowledgeable about the details, but I know that SAAMI considers them to not be interchangeable. The headspacing is different and I believe the 5.56 round is rated for higher pressures.

Hope this helps, though I am sure someone will post a more detailed answer shortly.

[Third_Rail]

5.56mm NATO standard has a slightly larger chamber, since dirt has a way of ruining a battle for people.

Ditto 7.62x51mm NATO, just a slightly larger chamber.


You can fire .223 and .308 in the NATO equivalent chambers, but DON'T fire NATO ammo in a .223 or .308 chamber - that slightly larger chamber is there for a reason other than just dirt; the 7.62 and the 5.56 can be larger (headspace wise, shoulder position, OAL) than a civilian chamber, leading to bad things.


EDIT: ah yes, greg700, "headspace", that was the word I kept leaving out. Glad you posted before me! Good catch on the pressures, too. 5.56 and 7.62 are rated to higher specs than .223 and .308.

[tcdrennen]

Edited to add: Beaten to the answer! :cool:

They are NOMINALLY the same round, but military specs and tolerances and SAAMI (commercial) specs and tolerances are NOT identical. What this means is that while milspec 7.62x51 or 5.56x45 chambers will accept commercial .308 Winchester or .223 Remington well enough, some "match grade" precision .308 or .223 chambers do NOT accept the mil surp rounds well.

I've seen finely tuned match .223 Rem AR extractors rip the heads right off milsurp 5.56x45 cases (leaving the case jammed in the chamber), and the headspacing on .308 Win rifles can cause some milsurp 7.62x51 to not go fully into battery.

So, before you buy 1000 rounds of milsurp for your match grade rifle, make sure the lot (yes milsurps vary between lots) will work in your gun.

[landon74]

Along with what everyone else said, 5.56 has a longer throat than .223 (from what I've been lead to believe) and 7.62x51 has a lower pressure rating from SAAMI than .308 Winchester does (55,000 vs 62,000).

If you look on Fulton Armory's website, the have FAQ's that thoroughly explain the differences in the cartridges........

[Art Eatman]

Back in the early days of the Mini 14, I knew some guys from Fort Hood who occasionally "liberated" some GI ammo for me. The Mini never seemed to think it was an improper diet. For that matter, neither does my Ruger 77 Mk II.

The shear-stregth lockup for a bolt action is stronger than for such as an M16. As near as I can tell, if the GI ammo is loaded to a higher pressure, the crimp keeps the primer from blowing. Dangfino.

I've found similar behavior with GI ammo in bolt action .308s: Zero problems. And, I guess, for the same reasons: The crimp around the primer pocket. After all, hunting rifles are proof-tested to some 90,000 psi or more.

The pressure limit for any brass cartridge case is the primer pocket and the restraint on the primer itself.

FWIW,

Art

[R.H. Lee]

IIRC the .223 commercial round is loaded to higher pressures than the 5.56 military ammo. .308 and 7.62 differ only slighty with regard to the shoulder angle, but otherwise are interchageable.

[Jim Watson]

Most of the differences are due to the military requirement for operation in harsh conditions with ammunition produced under wartime production and procurement.

There are some differences in military and commercial specification standards that have lead to stories of .308 Win being loaded a lot hotter than 7.62 military but there is no basis in fact.

I am sure you can get some unsatisfactory mismatches but I for one am not going to shoot cheap Slobbovian milsurp in my nice sporting rifles anyhow.

[Jim K]

There has been a lot written on the subject, along with DIRE WARNINGS!!! but I have never had any problem treating the 7.62 NATO and .308 Winchester as interchangeable, and the same with 5.56 military and .223 Remington, but will add that I am talking about equivalent bullet weights and loads.

Jim

[halvey]

I_Hunt_Liberals That name sure doesn't do a lot for our cause :o

[rritter]

Shooter's Carnival has a nice write-up here (http://carnival.saysuncle.com/002453.html) that goes into great detail about the difference between 7.62 NATO and .308 Winchester. Worth a read!

[g56]

Fact: SAAMI specifically warns against the use of 5.56mm ammo in .223 chambers. The .223 SAAMI specification was originally made with bolt rifles in mind.

http://www.saami.org/unsafe3.htm

For more technical information about the subject:

http://www.ammo-oracle.com/body.htm#diff

[Bravo11]

Not that this has anything to do with actual round comparision but I'll throw it out there anyway. Awhile back I was converting some dimensions on a drawing from metric to english. I saw the dimension 5.56mm and I noted that as .223" without doing the math because I have always equated 5.56 to .223. Wrong answer. After finding the screw-up the hard way I did the math and discovered that 5.56mm=.219" and .223"=5.66mm. :rolleyes:

[g56]

Since the .223 and the 5.56mm both use .224 bullets, that actually comes out to 5.69mm. :)

[Dave R]

Humph. How can such a simple thing get so complicated?

I shoot surplus 7.62 in my .308 Remington 700. I DO NOT shoot commercial .308 in my CETME, because I've heard tales of its vigorous extraction ripping commercial case heads off.

I shoot both NATO 5.56 and commercial .223 in my .223 AK (which was designed for 5.56 NATO). I have also shot 5.56 surplus in my .223 NEF Handi-Rifle, which did not seem to object. It just wasn't as accurate as .223 handloads or commercial varmit rounds.

[Mannlicher]

So what are you hunting liberals with anyway?

[R.H. Lee]

So what are you hunting liberals with anyway?
Probably Truth and Logic, both deadly to liberalism.

[DMK]

What I never understood is why are the milspec and SAAMI *cartridges* different?

I mean I can understand the chambers being designed tighter for sporting use and looser for .mil use, but why change the cartridge dimensions also?

As I understand it, the military 5.56 cartridge preceded commercial .223 right? Was this also true for the military 7.62 and comercial .308?

[ClarkEMyers]

If I recall anything like correctly the .308 was in fact originally a pure adaptation of the T-48 from the then Springfield Armory (and Springfield had a nod to the .300 Savage) but the cartridge/ chamber design was refined later. Again IIRC there is a difference in datum lines selected for dimensioning what could otherwise be the same drawings.

Current military autoloader designs (to expressly include civilian sem-auto versions) are much more likely to lightly tap the primers when cycling than commercial guns and that's something to keep in mind. Wouldn't surprise me that some fire in the clearing barrel accidents have happened from repeatedly chambering and rechambering the same cartridge on top of the magazine.
Without having it in writing from Ruger's lawyers I've heard suggestions that some commercial firearms are produced with military ammunition or dual use in mind and some are NOT.

FREX - and let me emphasis for example here, I like my Scout and other examples can be found -it is written but I haven't personally checked them all that the Steyr Scout was built with a slightly longer chamber (but carefully and deliberately controlled not at all by inadvertance and not overlength for commercial ammunition) to meet Cooper's desire for use of global pickup ammunition. Some have reported a need to increase the firing pin impulse on Scouts for use with hard primers as well. Note that that this is not a knock on the Steyr, such adjustments are provided for. Notice also that I think Redding and also Forster/Bonanza make different length (to be distinguished from small base which is different consideration) sizing dies for 7.62 Match ammunition and bolt guns in .308.

The 5.56 of course exists because the .222 Magnum wouldn't fit the AR-15 and the .223 would fit both the test rifles - see Ezell and others. Since it was a private development I'd say the .223 prototype came first there but it's semantics. Civilian development under the .223 name for a proposed military rifle IIRC.