Commercial Loads for 7.62x51mm?

[moonzapa]

Has anyone had good luck firing commercial 7.62x51mm ammo in their semi-auto's? I own two gas operated rifles that I have only handloaded for this cartridge. My buddy wants to get an AR-10 and he doesn't reload. I'm thinking the surplus Greek, Israel IMI, or British stuff earmarked "7.62x51mm" should be okay. Because of the higher pressures, no retail/commercial .308 Winchester ammo...Am I right or wrong?

Thanks!

 

[jonnyc]

Wrong. The .308 Win. IS the commercial disguise for 7.62x51, they are the same round. This is one of the most discussed issues on the internet, but there are still a few people out there that debate the facts. If you search a bit you will find lots more than you ever want to read.

 

[Caliper_Mi]

Wideners stocks it, but is out of stock at the moment

http://wideners.com/itemview.cfm?dir=18|830|848

While the case dimensions are the same, x51 has a longer allowable headspace (probably to help hot machine guns feed dirty ammo). This can produce an unsafe situation shooting 308 in a 7.62x51 rifle if the headspace is on the loose side for x51 (and thus out of spec for 308)

However I would hope that most modern AR10 and similar rifles are rated for both. Check with the owners manual or the manufacturer.

 

[Swampman]

moonzapa
You seem to have a fairly good grasp of what's required to keep your gas guns operating well for many years to come. It's not just a pressure thing, it's a pressure curve thing, along with a few other variables.
I believe that Federal and Hornady load ammo that has pressure curves and bullet weights designed to work with the gas systems on military rifles.

Anyone that truly thinks that there are NO differences between 7.62x51 and .308 Winchester should go buy themselves a nice new National Match M1A (with NO gas system mods) and a couple of cases of 200 grain (or 220 grain if it exists) Hornady Light Magnum Ammo and then have a ball!

PS: Don't worry about slamfires either, since the two rounds are identical, SAAMI specs have no doubt mandated that all .308 rounds loaded have cups designed to resist that sort of thing, even in rifles with dirty, wet or overlubed bolts!

 

[jonnyc]

"200 grain (or 220 grain if it exists) Hornady Light Magnum Ammo"

Not sure if I would call that your standard factory 7.62/.308 ammo. And any ammo compatibility issues with the M1A would tend to indicate a rifle concern, not an ammo concern.

 

[allaroundhunter]

7.62x51mm and .308 Win are interchangeable. Especially in an AR pattern rifle.

 

[W L Johnson]

Because of the higher pressures, no retail/commercial .308 Winchester ammo...Am I right or wrong?

The higher pressure myth comes from the way they were tested, 308 with the piezo method, 7.62x51(7.62 NATO) with the crush copper method.

The results were
308 62,000 PSI
7.62x51 50,000 CUP (Copper units of pressure)

People keep changing CUP to PSI in the case of 7.62x51 and start panicking. That's why you keep seeing 7.62x51 listed at 50,000 PSI when it should be 50,000 CUP
Tested the same way using the same units they're within a hair's breadth of each other.

As stated above the only real difference is the head space which is only a problem if you head space is borderline/

 

[Reloadron]

Has anyone had good luck firing commercial 7.62x51mm ammo in their semi-auto's? I own two gas operated rifles that I have only handloaded for this cartridge. My buddy wants to get an AR-10 and he doesn't reload. I'm thinking the surplus Greek, Israel IMI, or British stuff earmarked "7.62x51mm" should be okay. Because of the higher pressures, no retail/commercial .308 Winchester ammo...Am I right or wrong?

Thanks!

I guess we could kick the can a little further down the road on this subject. As mentioned the 308 Winchester and the 7.62 X 51 NATO are the same cartridge. The only difference I am aware of is chamber (not cartridge headspace) dimensions where the NATO chamber may be cut slightly larger exceeding commercial chamber specifications.

As to commercial ammunition? Take a look at the below image:



Let's take a closer look at the everyday inexpensive Winchester:



Note the box end flap. Winchester labels this stuff as both 308 Winchester as well as 7.62 X 51. I use this stuff in both my M1A and AR10 rifles and it shoots just fine. The Federal Gold Medal also shoots fine but carries a higher price tag.

In my commercial and also hand loads I stay at or below 180 grain bullets.

Beyond the pictured Winchester commercial stuff using 147 grain bullets there are other commercial ammunition loads out there from other manufacturers that will shoot just fine in service rifles. The Winchester is merely an example.

Just My Take
Ron

 

[R.W.Dale]

moonzapa
You seem to have a fairly good grasp of what's required to keep your gas guns operating well for many years to come. It's not just a pressure thing, it's a pressure curve thing, along with a few other variables.
I believe that Federal and Hornady load ammo that has pressure curves and bullet weights designed to work with the gas systems on military rifles.

Anyone that truly thinks that there are NO differences between 7.62x51 and .308 Winchester should go buy themselves a nice new National Match M1A (with NO gas system mods) and a couple of cases of 200 grain (or 220 grain if it exists) Hornady Light Magnum Ammo and then have a ball!

PS: Don't worry about slamfires either, since the two rounds are identical, SAAMI specs have no doubt mandated that all .308 rounds loaded have cups designed to resist that sort of thing, even in rifles with dirty, wet or overlubed bolts!

Hornady warns against the use of light magnum loads in ANYBODYS semiautomatic regardless of caliber or manufacturer

 

[moonzapa]

So, if I purchase commercial ammo for my AR-10 that has both the .308 and 7.62x51mm cartridges listed on the flap of the ammo box I shouldn't have to worry about the pressures being too high for my gas operated rifle. I have been warned by at least a dozen M1A, Garand, and AR-10 afficianados that to use commercial, over the counter, high intensity .308 Win hunting loads will absolutely shorten the life of the rifle; that commercial hunting loads are designed for strong bolt action rifles. I'm not hung up on either the .308 Win or 7.62x51mm moniker, and realize they are for all intents and purposes the same.

I reload and my buddy does not. I want to make sure when he goes to BassPro, Cabelas, Midwayusa, etc., to buy ammo for his semi-auto gas rifle, that he doesn't buy loaded ammunition that will short live his rifle, cause damage to it, or causes a catastrophic accident.

I apologize for not stating my concerns in a more concise manner. Really appreciate all of your comments and suggestions. Thanks!

 

[R.W.Dale]

If it's marked 308 on the box and doesn't also have warnings about semiautomatic firearms in general then you can shoot it to your hearts content.

Who makes a 7.62x51 ar10 anyways?

 

[allaroundhunter]

First off, the Garand is a different animal when it comes to shooting. It was designed around a .30-06 that produced much less pressure than current commercial .30-06 rounds. I will NOT shoot modern commercial ammo in my Garand (unless I change out the gas plug).

The AR10 will handle any commercial .308 Win ammo without a problem. Whether it says .308 Win or 7.62x51mm on the box, you're good to go. As has been mentioned, the over pressure myth comes from people not understanding the ways in which each round was measured (.308 in PSI and 7.62x51mm in CUP). When you measure each in the same units they are actually so close that they are interchangeable.

 

[Reloadron]

So, if I purchase commercial ammo for my AR-10 that has both the .308 and 7.62x51mm cartridges listed on the flap of the ammo box I shouldn't have to worry about the pressures being too high for my gas operated rifle. I have been warned by at least a dozen M1A, Garand, and AR-10 afficianados that to use commercial, over the counter, high intensity .308 Win hunting loads will absolutely shorten the life of the rifle; that commercial hunting loads are designed for strong bolt action rifles. I'm not hung up on either the .308 Win or 7.62x51mm moniker, and realize they are for all intents and purposes the same.

I reload and my buddy does not. I want to make sure when he goes to BassPro, Cabelas, Midwayusa, etc., to buy ammo for his semi-auto gas rifle, that he doesn't buy loaded ammunition that will short live his rifle, cause damage to it, or causes a catastrophic accident.

I apologize for not stating my concerns in a more concise manner. Really appreciate all of your comments and suggestions. Thanks!

You can use the Winchester I pictured earlier or Remington UMC and Federal also has several offerings under the American Eagle name.

Yes, as mentioned, the M1 Garand is a different animal when it comes to ammunition. While there are several commercial offerings they are fewer than what is available in 308 Winchester (7.62 NATO) loadings.

Ron

 

[powder]

OK,
#1.) The AR-10 is an ArmaLite, all the rest are something else: 716, M&P 10, etc...

#2.) The differences between .308 and 7.62 x 51 is not a myth.

ArmaLite builds THE AR-10s that are a 7.62 x 51, with several differing barrel lengths, chamber quality, and materials.

What rifle your friend is looking at is the more important variable: SIG, M&P, ArmaLite, etc., and the barrel length/twist, and the what the barrel is made of.

MilSurp is the better and more affordable avenue when you can find it, but beware of the OFV that is post '75, and there is a ton of other production variables to see in your researching ahead.

The 168gr loads seem to be a happy medium for most 7.62 x 51 rifle barrels, but as usual check with the manufacturer: there is no other manufacturer which details these matters such as ArmaLite. Check their website and the TechNotes.

 

[moonzapa]

R. W. DALE: My Armalite AR-10 is inscribed, "7.62x51mm". I pulled up the .308 Winchester Cartridge Guide from www.6mmbr.com/308win.html. It revealed the following on page 9 of 12:

308 Win vs. 7.62x51

The Straight Scoop

Before we go much further, we want to address the oft-posed question "Are the .308 Winchester and 7.62x51 NATO one and the same?" The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635 for the 7.62x51. The .308's "No Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "Nobody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62mmx51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max...
Nuff said...

 

[MistWolf]

Before insisting the 308 Winchester makes more chamber pressure than the 7.62x51, you'd better know how the pressure for each is measured. CUP and PSI cannot be directly compared. Even if both were measured in PSI, they may not be directly compared because the two methods may not be measured at the same place using the same sensors.

Plus, the headspace of the NATO chamber is slightly greater than the SAAMI chamber. This will REDUCE pressure because the brass will expand to a larger internal volume

 

[allaroundhunter]

Okay moonzapa, you win. Go with that article, but it is wrong. Again, it is following the myth that CUP and PSI are the same unit of measure which they are not.

 

[R.W.Dale]

R. W. DALE: My Armalite AR-10 is inscribed, "7.62x51mm". I pulled up the .308 Winchester Cartridge Guide from www.6mmbr.com/308win.html. It revealed the following on page 9 of 12:

308 Win vs. 7.62x51

The Straight Scoop

Before we go much further, we want to address the oft-posed question "Are the .308 Winchester and 7.62x51 NATO one and the same?" The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635 for the 7.62x51. The .308's "No Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "Nobody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62mmx51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max...
Nuff said...

That article is almost ten years old and does in fact repeat the same erroneous assumption that cup = psi.

Think about it. A 50k psi cartridge would have performance closer to 30-30 than it would 308 if that's the pressures it was loaded to.

 

[Reloadron]

moonzappa:

My Armalite AR-10 is inscribed, "7.62x51mm".

Where is it inscribed? The reason I ask is my AR-10(T) is only marked Rifle 7.62MM as can be seen in the below image. The rifle is about 20 years old and right after I got it I replaced the barrel retaining the original barrel and floated hand guard. The original barrel has zero markings as to chambering.

Looking at Armalite current offerings they seem to use terms like:

Chamber: ArmaLite Match
Semi-Auto
Model: AR-10(T) with Free Float Handguard in Black
Caliber: .308/7.62 X 51mm NATO

So while I see 7.62MM I am not seeing 7.62MM X 51 or 7.62MM NATO for example. Again, this example is 20 years old or so and I haven't shot the rifle much over the past 12 to 15 years.

Ron

 

[W L Johnson]

From Armalite tech note #74

NOTE: ArmaLite’s® larger AR-10 series rifles are all chambered with 7.62 NATO chambers. .308 Winchester (SAAMI standard) ammunition functions perfectly in the 7.62 NATO chambers.

 

[W L Johnson]

Even the big boys mix up units.
NASA lost a $125 million mars orbiter because one set of engineers was using feet and another meters. Whoops

 

[W L Johnson]

Tell you what, if you have a semi auto 7.62x51 and some 308 ammo that you feel shouldn't be shoot out of it, send me the ammo and I will dispose of it for you free of charge.

 

[powder]

Well, somebody better tell the boys at Hodgdon that they don't know what they're talking about either?!

http://data.hodgdon.com/cartridge_load.asp

 

[HOOfan_1]

Well, somebody better tell the boys at Hodgdon that they don't know what they're talking about either?!

http://data.hodgdon.com/cartridge_load.asp

What are we supposed to be seeing in that link?

 

[35 Whelen]

R. W. DALE: My Armalite AR-10 is inscribed, "7.62x51mm". I pulled up the .308 Winchester Cartridge Guide from www.6mmbr.com/308win.html. It revealed the following on page 9 of 12:

308 Win vs. 7.62x51

The Straight Scoop

Before we go much further, we want to address the oft-posed question "Are the .308 Winchester and 7.62x51 NATO one and the same?" The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635 for the 7.62x51. The .308's "No Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "Nobody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62mmx51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max...
Nuff said...

This is crazy. I haven't referenced this article on this very subject in months...maybe longer, then suddenly three times in one day!! Read it. Learn it. Remember it. Reference it.

35W