7.62X51mm in 308 AR

[trapper9260]

Hi I like to know can you shoot 7.62X51mm in a chamber of 308 of a AR Thank you

[Larry Gibson]

And why wouldn't you be able to?

Larry Gibson

[Doc Highwall]

Yes you can, I suggest you look under the military rifle section for a sticky by Bruce B. about shooting cast in a M1A out to 400 yards.

[dragon813gt]

And why wouldn't you be able to?

Larry Gibson

I'm assuming the OP is thinking that since it's not marked for the NATO designation that it might not be safe? Same question gets asked all the time about shooting 5.56x45 in one marked 223.

[trapper9260]

Thank you for letting me know, I was not sure and did not know where to find what was writtien on it that is why i ask.may also ask that you can also then shoot 7.62Nato then .

[Multigunner]

Hi I like to know can you shoot 7.62X51mm in a chamber of 308 of a AR Thank you
Check the chamber specifications the manufacturer used.
Look for a list of recommended ammo types.
Some manufacturers have gone to a generic chamber that has just enough slack to accommodate milsurp 7.62 NATO ammo of uncertain origin while others had used a tight commercial .308 chamber for best accuracy.
Its not a matter of pressure of the cartridge.
Acceptance standards of NATO ammo is a bit more broad than SAAMI standards for the .308.
Bullet ogive profile of milspec bullets can be fat and crowd the throat, or bullets may be undersized. Cases are some times fat as well.

About the worst that could happen is an out of spec (by SAAMI standards) 7.62 cartridge jamming in the tighter .308 chamber.

On the other hand .308 sporting ammo does not have crimped primers and primer cups not up to milspec , these may cause backed out or blown primers or slamfires in some military autoloaders.

Some Military autoloaders don't function well with sporting ammo powders of some .308 cartridges. Some don't function well with all types of 7.62 ammo powders for that matter. Differences in burning rates can cause excessive gas port pressures with early unlocking, resulting in torn off case rims or separated cases.


If the 7.62 ammo you wish to use (provided its reasonably fresh) chambers freely in a .308 marked modern autoloader there should be no problems, though accuracy may not be up to snuff.
Theres a boat load of poor quality 7.62 NATO ammo on the surplus market. If it was good ammo it would not have been culled by inspectors. Some was great ammo when manufactured, but spent decades in storage in tropical climates.
I've broken down degraded 7.62 ammo for components and had to trash most of it due to cases corroded through from the inside, degraded powder that ate through a steel can, and gilding metal peeling off steel jacketed bullets.
In fact the worst milsurp ammo I've encountered so far was 7.62 NATO.

[trapper9260]

Check the chamber specifications the manufacturer used.
Look for a list of recommended ammo types.
Some manufacturers have gone to a generic chamber that has just enough slack to accommodate milsurp 7.62 NATO ammo of uncertain origin while others had used a tight commercial .308 chamber for best accuracy.
Its not a matter of pressure of the cartridge.
Acceptance standards of NATO ammo is a bit more broad than SAAMI standards for the .308.
Bullet ogive profile of milspec bullets can be fat and crowd the throat, or bullets may be undersized. Cases are some times fat as well.

About the worst that could happen is an out of spec (by SAAMI standards) 7.62 cartridge jamming in the tighter .308 chamber.

On the other hand .308 sporting ammo does not have crimped primers and primer cups not up to milspec , these may cause backed out or blown primers or slamfires in some military autoloaders.

Some Military autoloaders don't function well with sporting ammo powders of some .308 cartridges. Some don't function well with all types of 7.62 ammo powders for that matter. Differences in burning rates can cause excessive gas port pressures with early unlocking, resulting in torn off case rims or separated cases.


If the 7.62 ammo you wish to use (provided its reasonably fresh) chambers freely in a .308 marked modern autoloader there should be no problems, though accuracy may not be up to snuff.
Theres a boat load of poor quality 7.62 NATO ammo on the surplus market. If it was good ammo it would not have been culled by inspectors. Some was great ammo when manufactured, but spent decades in storage in tropical climates.
I've broken down degraded 7.62 ammo for components and had to trash most of it due to cases corroded through from the inside, degraded powder that ate through a steel can, and gilding metal peeling off steel jacketed bullets.
In fact the worst milsurp ammo I've encountered so far was 7.62 NATO.

Thank you for explain it all to me

[Larry Gibson]

I'm assuming the OP is thinking that since it's not marked for the NATO designation that it might not be safe? Same question gets asked all the time about shooting 5.56x45 in one marked 223.

Is not 7.62x51 the European designation for .308W? 7.62 NATO if loaded to NATO specs should be marked as such and have the "+" symbol on the headstamp. I also did not see where the OP mentioned 7.62 NATO(?).

Larry Gibson

[Multigunner]

Is not 7.62x51 the European designation for .308W? 7.62 NATO if loaded to NATO specs should be marked as such and have the "+" symbol on the headstamp. I also did not see where the OP mentioned 7.62 NATO(?).

Larry Gibson

If he had meant European sporting ammunition I think he would have said so. His reply to my post indicates he understood what I meant.

Also while he said .308 AR he did not make it clear whether he meant the Armalite manufactured rifle, a clone, or any such rifle using a barrel not made to Armalite specifications.
A barrel with tighter than average target chamber could have problems with 7.62 NATO milsurp ammo.
When I bought my Remington 788 in .243 I had been planning on buying a .308 so I could use 7.62 milsurp ammo but the store owner told me he couldn't sell the rifle in .308 till Remington settled some issues of damage caused by use of 7.62 ammo in the .308 chambers. IIRC the throat (and possibly the neck) of the early production Remington chamber was on the tight side causing excessive pressures when some milsurp 7.62 ammo was used. This sometimes resulted in lug set back, cracked or broken lugs, and bolt handles breaking off due to difficulty in opening the action.

[exile]

If he had meant European sporting ammunition I think he would have said so. His reply to my post indicates he understood what I meant.

Also while he said .308 AR he did not make it clear whether he meant the Armalite manufactured rifle, a clone, or any such rifle using a barrel not made to Armalite specifications.
A barrel with tighter than average target chamber could have problems with 7.62 NATO milsurp ammo.
When I bought my Remington 788 in .243 I had been planning on buying a .308 so I could use 7.62 milsurp ammo but the store owner told me he couldn't sell the rifle in .308 till Remington settled some issues of damage caused by use of 7.62 ammo in the .308 chambers. IIRC the throat (and possibly the neck) of the early production Remington chamber was on the tight side causing excessive pressures when some milsurp 7.62 ammo was used. This sometimes resulted in lug set back, cracked or broken lugs, and bolt handles breaking off due to difficulty in opening the action.

Thank you for this information. I have been thinking about a Savage. 308 Hog Hunter, assuming in a pinch I could shoot surplus 7.62 through it. Does anyone know of a bolt rifle that would be safe with 7.62 x 51? Sounds like maybe not huh?

[exile]

Sorry, 7.62 NATO milsurp.

[ElDorado]

I don’t think the caveat about 223 Remington vs 5.56 NATO applies to 7.62 NATO, with the exception that multigunner talked about. I always like to refer to SAAMI’s “Unsafe Firearm-Ammunition Combinations” publication. They list “5.56 Military” as being unsafe in a firearm chambered in 223 Remington, but there’s no similar warning for 308 Winchester chambers.

http://www.saami.org/specifications_and_information/publications/download/SAAMI_ITEM_211-Unsafe_Arms_and_Ammunition_Combinations.pdf

So I think multigunner is right. If it fits in the chamber, it will probably be okay. He’s also right about crappy milsurp ammo out there, and I suspect some of it is corrosive. Personally, I wouldn’t shoot milsurp unless it was American. I have a Smith Enterprises M14 and a Winchester Model 70 and I only shoot my own handloads with IMR 4895 (no cast loads, yet).

[Larry Gibson]

Thank you for this information. I have been thinking about a Savage. 308 Hog Hunter, assuming in a pinch I could shoot surplus 7.62 through it. Does anyone know of a bolt rifle that would be safe with 7.62 x 51? Sounds like maybe not huh?

All factory rifles chambered for the .308W are safe to shoot 7.62 NATO ammunition in. Never heard of the Remington "case"; anyone have the court #?

It is a myth that 7.62 NATO ammunition is unsafe in .308W chambers and many times you hear it that .308W is unsafe in 7.62 NATO chambers.....depends on who is repeating the myth and which internet site he is quoting. I have actually measured the pressures of numerous lots of foreign and US made M80, M118 and M118LR and numerous different makes of .308W factory ammunition in 3 different rifles all with tight match spec .308W chambers. I can show you 7.62 NATO ammunition that gives higher psi's than most .308W ammunition and conversely I can show you .308W ammunition that gives higher psi's than most 7.62 NATO ammunition. For all intents and purposes of pressure safety they are the same cartridge falling within the same SAAMI psi MAP for the .308W. They are all safe in .308W match chambers let alone the looser spec chambers of most commercial and military chambered bolt guns. BTW; The M24 and M40A series of bolt action sniper rifles are head spaced and chambered to .308W match specifications. They shoot a bajillion round of .308W match and military 7.62 NATO ammunition through those every year.

That either type of ammunition is dangerous in either type of chamber is a myth, I don't care how "prestigious" the site's author is. Unless they have actually measured the psi of both in both types of chambers they are just guessing.......and their guess is wrong. None of the so called "expert" sites I've read have actually measured any pressures of either. They base their "guess" off chamber specs and published psi's, many times confusing CUP with psi, and come to the wrong conclusion. Most often it is simply done to "prove" a conclusion they have already predetermined w/o actually testing anything.

Larry Gibson

[Multigunner]

They are all safe in .308W match chambers
Go tell that to the NRA UK, the Birmingham Proof Authority, and Radway Green.
http://www.border-barrels.com/articles/Pressure_Trials_Consortium.htm


CONCLUSIONS and RECOMMENDATIONS
The main conclusion of these trials is that tight barrel dimensions and in particular, tight throat dimensions can cause significant increases in chamber pressures.

It was shown that with decreases in barrel and throat dimensions of the order of 1%, all the varieties of ammunition tested were shown to have their sample Peak Pressure average increased well beyond the 4150 bar limit for C.I.P. approved ammunition, despite having reasonable working pressures below this limit in a standard test barrel.

Barrels with a bore dimension of .298" and a groove dimension of .3065 are typical of a large number, if not the majority, of barrels used in the sport of Fullbore Target Rifle shooting. Most of these barrels have throat diameters of .3085" or less. Commercially available, C.I.P. approved ammunition could be potentially dangerous in rifles with tight throat and barrel dimensions.

Match rifles used at Bisley must now pass chamber inspections to insure the neck and throat are not too tight.
More modern milspec auto loaders have far higher safety margins than most pre WW2 bolt actions, so the rifle isn't likely to suffer a catastrophic failure, but excessive pressure repeated many times can cause premature wear of working parts. There's more than one reason why milspec chambers are on the max side.

With the world wide military operations of today, no NATO country is going to dump surplus 7.62 on the market unless its of too low a quality to be used in MG training. Even then they gift it to third world allies when possible.

[Larry Gibson]

Multigunner

I said (very first sentence) "All factory rifles chambered for the .308W are safe to shoot 7.62 NATO ammunition in." I did not say they were safe in chambers in non factory made match rifles specifically with tight necks and short throats made for one specific kind of ammunition, specifically as done in England. A standard match spec chamber here in the good old USA is made to minimal SAAMI specs BTW and the chambers you refer to, as cut in England and/or used in England, are specifically ordered in very, very few rifles made for their specific type of shooting. I don't think you're going to find such a chamber in a .308W AR which is what the OP asked about because that rifle is neither used for that type of shooting, assuming you mean the really long range shooting such as Palma or Bisley matches, in England or here. Nor did the OP say he was in the UK, had bought the AR in the UK or was going to use Radway Green ammunition (quite safe in factory .308W chambers btw.....I have shot a bit of it and pressure tested it....have you?).

So kindly show me/us where the NRA UK, the Birmingham Proof Authority, and Radway Green say either ammunition is unsafe in standard SAAMI and CIP .308W chambers or standard NATO milspec chambers?

With the world wide military operations of today, no NATO country is going to dump surplus 7.62 on the market unless its of too low a quality to be used in MG training. Even then they gift it to third world allies when possible.

So England still considers us a third world ally? If not seems they "dumped" a lot of very good, quite accurate and very serviceable Radway Green 7.62 NATO ammunition on us several years back. That ammunition brings a real premium price on the market these days. Could it possibly be that numerous NATO countries have sold a lot of 7.62 NATO and non-NATO spec ammunition to surplus dealers simply because it is no longer needed for war stockage since they all went to 5.56 NATO? Perhaps it all wasn't "dumped", because of low quality, on the market after all but simply sold because it was surplus? Could that not be.......considering the excellent quality of the surplus Radway Green and some other foreign 7.62 NATO ammunition I've tested which met or had better internal ballistics and accuracy than our own 7.62 NATO M80?


Larry Gibson

[Multigunner]

So kindly show me/us where the NRA UK, the Birmingham Proof Authority, and Radway Green say either ammunition is unsafe in standard SAAMI and CIP .308W chambers or standard NATO milspec chambers?

Why?
While chambers built to minimum SAAMI standards should be safe, remember that SAAMI standards are voluntary in the USA. Theres no guarantee that a custom aftermarket barrel will adhere to SAAMI specifications unless the manufacturer puts that in writing. Armalite does put its guarantee of a milspec chamber in writing.

If we could be sure that every AR-10 clone met the specifications that would be great.



Nor did the OP say he was in the UK, had bought the AR in the UK or was going to use Radway Green ammunition (quite safe in factory .308W chambers btw
Which is what the report I linked to stated, the increased pressures were with custom matchgrade barrels using throats that were too tight, basically the same situation Remington ran into when using a tight short throat in the early production 788 chambers.
Considering the reputation for high degree of accuracy of the Remington 788 have you ever wondered why so few were ever built up as long range match rifles?
Ever wonder why so many ended up having the bolt handles tig welded back on?

My comments were towards his being sure of the chamber specs of his rifle, rather than taking anything for granted.

PS
I forgot to add that early production Radway Green 7.62 144 grain Ball ammo has a .3075 bullet. Later production 144 and 155 gr ammo used a .3085 bullet such as that used by U S manufacture 7.62 ammo.
Older surplus Radway Green ammo was at one time distributed by the NRA UK for match competition.
This is one reason why UK target shooters preferred undersized bores and undersized throats.
Undersized bores and throats have also been used by long range shooters to minimize blowby when using boat tail bullets.
The practice is safe enough if you are careful what ammo you use.

And some 7.62 NATO ammo has a very spotty reputation for quality of manufacture and much of that has degraded in storage.
The rash of blown up Spanish Mausers was almost entirely due to a bad lot of Santa Barbra 7.62 ammo (some of this ammo generating proof cartridge pressures with every shot), and CBC 7.62 ammo caused dozens of blown up rifles of all types. Last I heard litigation is still going on in that case.
PMC marked 7.62 has also been subject to bad lots.

[MtGun44]

Yes.

Bill

[tomme boy]

I'm with Larry on this one. The Parker Hale Target rifles were the only ones with the tight bore barrels. They were also not available to the general public. It all had to do with the 155 gr max bullet weight for the palma rifles. Custom all the way.

[Doc Highwall]

My palma barrel is .306" x .298"

[Multigunner]

The Parker Hale Target rifles were the only ones with the tight bore barrels. They were also not available to the general public.
There are lists of manufacturers of tight bore .308 barrels. Parker Hale are not the only manufacturers of tightbore matchgrade barrels.

The NRA UK list Ferlach, Maddco, and Krieger barrels among those that should be checked to insure the throat meets NRA specifications.

Early Enfield manufacture FN FAL barrels also have undersized bores. This was to insure longer bore life in full auto or rapid semi auto fire.

[BruceB]

"They were also not available to the general public."

Well, I owned a Parker-Hale 1200TX .308 target rifle. It had a 28" medium-heavy barrel and P-H match sights, and a fore-end rail with handstop....all from the factory. It was built on a '98Mauser-type action, with adjustable P-H trigger and a charger guide for loading from standard NATO stripper clips. I'd say say that constitutes a "target rifle", and I was most certainly a member of the (Canadian) public.

This rifle pre-dated my interest in cast rifle bullets, so I never bothered to slug the barrel. I will say, though, that it shot both Hornady and Sierra commercial bullets with superb accuracy.

I wish I still owned it!

[Larry Gibson]

All is terrific and a great conversation but what does tight bores of English long range bolt actions rifles and Radway Green ammunition of yesteryear have to do with shooting milsurp in an AR with a standard .308W chamber?

Larry Gibson

[Multigunner]

All is terrific and a great conversation but what does tight bores of English long range bolt actions rifles and Radway Green ammunition of yesteryear have to do with shooting milsurp in an AR with a standard .308W chamber?

Larry Gibson

Nothing if the AR in question has a milspec 7.62 chamber like Armalite guarantees their rifles have.
I suggested the OP check the specifications on the website of the manufacturer and that goes for manufacturers of aftermarket barrels if his rifle happens to have one.

The rest was in answer to possible misconceptions about standardization of chamber and throat dimensions and ammunition from a legion of manufacturers.
As mentioned participation in SAAMI is voluntary. Some manufacturers of after market barrels may not abide by SAAMI standards, and some may subcontract barrels from foreign sources. Aftermarket M1A barrels have occasionally shown problems. The AR-10 and its clones are probably a much smaller market.

With the ease of interchangeability of AR parts one must be careful to be sure just what parts may be on a second hand AR. New from the factory should be no problem.

Also while unsuitable ammunition may not always cause catastrophic failures it can cause excessive wear and very expensive repairs. If used in more serious circumstances ammunition induced jams or breakages could cost a life.
The fiasco of substituting an unsuitable ball powder for the specified IMR in 5.56 ammo taught that lesson at great price.
Excessive gas port pressures caused excessive wear, jams and breakages.

Not all 7.62 or .308 ammo has the same characteristics, and some is not suitable in all types of autoloading mechanisms under the best of circumstances.

[Larry Gibson]

You win. Probably shouldn't shoot any ammo of either type, commercial .308W or milsurp 7.62, or especially those often dangerous "reloads". If the OP doesn't shoot anything the AR will last forever and he won't have to worry about parts breakage, catastrophic failures, parts breakage, the wrong powder, etc. ad nauseum.......might as well take up golf.........

Larry Gibson

[Multigunner]

The OP has asked for advice and information, and he got that.
So long as he feeds his rifle suitable ammunition the rifle will give many years of service. If he feeds it junk ammo it might not last through a full magazine, or end up spending far more time at a gunsmith's shop than at the range.
An AR-10 is quite an investment, so long as Uncle Sugar is not paying the bills its only common sense to be very picky about the ammo you feed it.

So long as the rifle has the milspec chamber, as Armalite AR-10s normally have, he should have no difficulty with quality manufactured and fairly fresh NATO spec ammo.
Junk bargain basement ammo has ruined many a rifle.


PS
Just got through reading some posts on another board about Savage lever actions jamming and showing pressure signs when surplus 7.62 NATO was used.
Apparently these also had the short tight throat that the Remington 788 had with the same results when milspec 7.62 was used in a tight .308 chamber.

[gew98]

You win. Probably shouldn't shoot any ammo of either type, commercial .308W or milsurp 7.62, or especially those often dangerous "reloads". If the OP doesn't shoot anything the AR will last forever and he won't have to worry about parts breakage, catastrophic failures, parts breakage, the wrong powder, etc. ad nauseum.......might as well take up golf.........


Larry Gibson

Larry I feel your pain for the wikimongers among us as they know so much from reading and no damn practical experiance.

[blikseme300]

Larry I feel your pain for the wikimongers among us as they know so much from reading and no damn practical experiance.

I'm going to take up golf. It is too dangerous to shoot anything...

[Multigunner]

Larry I feel your pain for the wikimongers among us as they know so much from reading and no damn practical experiance.

Gew98 you are acting like a child.
You've told us of the rifles you managed to wreck in the past so the best you can do is act as an example of poor gun handling and the effects of blind ignorance. Your gun handling experiances are more cautionary tale than anything else.
I'm still waiting for your evidence to support your claim that the Sten Gun walks away with all the prizes at Knob Creek. I'm beginning to wonder just how many of your "experiances" are actually your own or just stuff you've read or heard others claim.

Its good that you stick to the Mausers, they were designed to be idiot proof and to hold up under abuse by ham handed peasants.

The OP asked a simple question which was answered within the first few posts. The rest of this thread seems to be straw man personal attacks and attempts to steer people away from the carefully done research of cartridge manufacturers and proof house authorities.
You'd much prefer that your anecdotes be taken as authoritative and in your fevered imagination you see yourself as an authority.
Best you visit your doctor and have him adjust your Alzheimers medication, it doesn't seem to be working.
When someone wants instructions on how to wreck a perfectly good rifle we will call you.

[gew98]

I'm going to take up golf. It is too dangerous to shoot anything...

By god..golf I won't do !. Can't fathom chasing a little ball around alot of acreage with no discernable practical purpose.