7.62x51 vs. .308 Discussion

M14s, M1 Garands & Carbines, Enfields, M1903s
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Plucky Purcell
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7.62x51 vs. .308 Discussion

Post by Plucky Purcell » Sun Mar 06, 2005 5:29 pm

Here's what I found to start this discussion:

7.62x51mm NATO or 308 Winchester?

308 Winchester Gauges
GO - 1.6300"
NOGO - 1.6340"
FIELD - 1.6380"

7.62x51 Military Gauges
GO - 1.6350"
NOGO - 1.6405"
FIELD - 1.6455"

There is a .013" difference in chamber length however, between these two "Safe & Serviceable" rifles!


Military brass is thicker. It needs to be. It was made to function and stretch in a wide variety of firearm chambers. Don't forget that the condition of spent brass is of no importance to the service. Like 99% of military brass, it won't be reused.


Military ammunition is loaded to maximum average pressure 50,000 PSI using the modern piezo transducer method of measurement. This standard is used to ensure better consistency round to round. It is proofed at 67,000PSI. The ammunition can then be used in a wide variety of firearms with no ill effects.

Commercial ammunition has a SAAMI/ANSI maximum pressure of 62,000PSI. While not every manufacturer may load it to this level, this is the industry established maximum. This is also measured using the piezo transducer method. The proof cartridge pressure is 83,000 to 89,000 PSI. Note the differences between the military test and operational standard vs the commercial one.
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Post by 305 Fal » Sun Mar 06, 2005 6:07 pm

I for one think that in military semiauto rifles one should stick with what they were designed for 7.61 x 51 mm NATO ammo.
Likewise in commercial rifles one should use commercial 308 Winchester ammo.
If all of the manufacturers, distributors and dealers were a little bit more informative about these differences, it will save people a lot of hassle.

Great post by the way =D>

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Post by mjmensale » Mon Mar 07, 2005 10:09 am

Here's some thoughts from Fulton Armory on the subject.

Basically, any miltary pattern rifle with a 7.62mm military chamber can safely handle NATO spec ammunition. That's what they were designed for! M14/M1A, FAL, HKG3/HK91, Galil, etc. Unless you have a POS parts gun built from crappy parts, there is no reason not to use 7.62mm NATO ammo in it.

Reloading the brass shouldn't be an issue either as the surplus stuff is so cheap is doesn't matter if it's Berdan primed (non-reloadable).

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What's the Difference between .308 Winchester & 7.62x51mm NATO?
by Clint McKee and Walt Kuleck

--------------------------------------------------------------------------------
dumb question i alway thought these 2 ammos where interchangeable but some have told me otherwise whats the story??? jim

Hi, Jim,

This is a perennial topic, kinda like ".45 vs. 9mm" or "Best Guns & Loads for Deer."

They are not the same.

They are the same.

They are not the same, 'cause the .308 Win was released by Winchester several years before the Army standarized the T64E3 as the 7.62MM. You'll get an endless discussion of pressure specs, endless because SAAMI and the Ordnance Dep't measured pressure in different, unrelateable ways. Howver, the chamber drawings are different.

They are the same, 'cause nobody (and Clint's been looking for many years!) makes 7.62MM ammo that isn't to the .308 "headspace" dimension spec. So 7.62MM ammo fits nicely into .308 chambers, as a rule.

But in some 7.62MM rifles the chambers are long (to the 7.62MM military spec), notably the Navy Garands with 7.62MM barrels. Thus, using commercial ammo in such a rifle is not a good idea; you need stronger brass. Use military ammo or the best commercial only, e.g., Federal Gold Medal Match.

Most of the time it's a distinction without a difference. But if you intend to shoot .308 commercial in a military arm chambered for 7.62MM, first check the headspace with .308 commercial gauges first. You may get a surprise.

Best regards,

Walt Kuleck
Fulton Armory webmaster


--------------------------------------------------------------------------------
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
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Post by Sabot 23 » Mon Mar 07, 2005 10:11 am

Anyone can read my past posts on this subject and see my learning experience unfold. #-o

I used to routinely fire hot-loaded comercial .308 as well as hot-loaded handloaded .308 rounds from my Stg-58 FAL. It should be noted that I fired several hundred of these hot loads with no problems. Then, of course, I did have a problem. I blew my bolt. [-X ](*,)

I was lucky, all I needed to do to get her up and running again was to install a new bolt. Since then, I have only fired either milsurp (LC USGI) or reloads using either .308 brass or LC 7.62 NATO brass loaded down to well below max.

I figure pressure usually roughly translates into velocity, within a given bullet style/weight. The surplus I've been shooting chronos at about 2750 fps with a 147gr fmj. I also use a 147gr fmj in my reloads, and I load them to about 2700 fps, give or take. Still a nice, warm load for a .308. As a guideline I use the loading data for a 150gr jacketed bullet, and for that matter, I use the data for AA2230, but I actually load with the AA2230C, which has a slightly slower burn rate. I notice less wear and tear on my brass, less trimming of the cases is needed, easier to collect spent brass, ect. And let's face it, in any real-world incident, be it hunting deer, or defending one's neighborhood in a riot, is a velocity loss of 100fps or so ever really going to make any difference? And it may make all the difference to your rifle and it's bolt, at least.
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Post by Plucky Purcell » Mon Mar 07, 2005 5:22 pm

mjmensale wrote:Basically, any miltary pattern rifle with a 7.62mm military chamber can safely handle NATO spec ammunition. That's what they were designed for! M14/M1A, FAL, HKG3/HK91, Galil, etc. Unless you have a POS parts gun built from crappy parts, there is no reason not to use 7.62mm NATO ammo in it.
Exactly.

Getting away from all the numbers, it's like this...

Milsurp 7.62x51 ammo should run excellent in any military firearm chambered for that cartridge and it will work fine in commercial rifles chambered for 308 Winchester. However, as Sabot23 learned the hard way, trying to run higher pressure and thinner casing commercial 308 Winchester in military firearms chambered for 7.62x51 NATO will eventually lead to problems.

BTW.
Pressure = Force/Area
Force = Mass x Acceleration
Acceleration = Change in Velocity / Change in Time

so...

Pressure = [Mass x (Change in Velocity / Change in Time)] / Area

Since bullet mass and diameter (for area) stays the same, then in this case Pressure is proportional to Velocity.

Of course there's PV=nRT, but that's really for fluids. :smile
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Post by glockpacker » Mon Mar 07, 2005 6:07 pm

Well, I'd say that discussion ended well.

:smile

But I still don't have a .308.

#-o
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Post by FIUMAN1 » Mon Mar 07, 2005 7:09 pm

Well, I can think of some rifles, chambered for 7.62x51mm NATO, where the use of commercially loaded .308 Winchester is not a smart move. In particular the Israeli K98k and the Spanish FR-8. Given some time I could come up with some others. In conclusion, one CAN make the statement that .308 Winchester should not be fired in rifles designed to fire 7.62x51mm NATO due to potential safety issues. The use of 7.62x51mm NATO in rifles designed for .308 Winchester should not pose a problem, on the other hand.

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Post by Plucky Purcell » Mon Mar 07, 2005 9:44 pm

glockpacker wrote:
But I still don't have a .308.

#-o
Then you've just gotta get one. Whatever you do though, DON'T GET A FAL. Once you get one FAL, you are constantly struggling with some internal need to get another, then another. It's a horrible addiction. First you innocently buy a metric Stg58. Then you end up with a Austrialian L1A1 and then a G1. Then a Brit L1A1 and a Canadian L2. Before you know it you are scrounging the web for Izzy parts and hiding away funds from the wife hoping somone will put a mint G series up for sale. It's horrible I tell ya!

My name is Bob, and I'm a FALcoholic. :smile
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Post by mjmensale » Tue Mar 08, 2005 2:43 pm

HI, BOB! =:bye =:bye =:bye

Moe
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Post by Casual » Wed Apr 06, 2005 6:20 pm

mjmensale wrote:HI, BOB! =:bye =:bye =:bye

Moe
LOL!!!
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Post by mike'nat » Tue Apr 18, 2006 10:49 pm

can we start a 12 step.

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Re:

Post by JOEBOB » Fri Jan 02, 2009 9:59 am

FIUMAN1 wrote:Well, I can think of some rifles, chambered for 7.62x51mm NATO, where the use of commercially loaded .308 Winchester is not a smart move. In particular the Israeli K98k and the Spanish FR-8. Given some time I could come up with some others. In conclusion, one CAN make the statement that .308 Winchester should not be fired in rifles designed to fire 7.62x51mm NATO due to potential safety issues. The use of 7.62x51mm NATO in rifles designed for .308 Winchester should not pose a problem, on the other hand.
Good post, Plucky
Actually, Fiuman, Izz 7.62 mausers and FR-8s are almost certainly OK with .308. They're large ring mausers on military spec receivers with bolt raceways that do not extend thru the receiver rings. They handle 60+k PSI just fine.Just look at the number of sporters in .270 built on these. Some commercial Mausers, such as the FN made postwar Mausers, have a bolt lug raceway that extends thru the receiver threads, and they're still plenty strong for 60K+ PSI.

On the other hand, the small ring mausers, such as the FR-7 and Guardi Civil Mausers shouldn't be fired with the .308 loads, as they don't necessarily have the strength or metallurgy to provide long service or enough of a safety margin. The same goes for Ishapore Enfields, FALS, and to some extent the CETME/G3 family. Milspec brass is also a good idea in autoloaders.

I load all of my .308/7.62 to 7.62 spec, trying for 2700 FPS with 150 grain Remington PSPCL bullets and appropriate powders ( I usually get more like 2600+ FPS because of the necessity of reducing charges in Military brass). Data that lists pressures is helpful when you know that a 10% reduction in powder charge nets ABOUT an 8% pressure reduction.
This bullet at this speed is good for everything in the lower 48. A 180 grain Remington PSPCL or 165 Barnes X loaded to 50K PSI should be adequate in a pinch for even Kodiaks, although I would prefer the PSPCL or an 180 grain X bullet with 200 to 400 FPS more out of a 30-06 or .300 magnum

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Re: 7.62x51 vs. .308 Discussion

Post by mjmensale » Fri Jan 02, 2009 8:18 pm

Nothing like resurrecting a nearly 3 year old thread! [smilie=pdt_xtremez_30.gif]
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Re: 7.62x51 vs. .308 Discussion

Post by zendick » Wed Apr 15, 2009 3:48 pm

low recoil ammo, of the like from Remington etc is safe to fire in 7.62nato rifle (the low recoil is achieved by drastically reducing pressure)
like this
http://www.remington.com/products/ammun ... recoil.asp" onclick="window.open(this.href);return false;

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Re: 7.62x51 vs. .308 Discussion

Post by SGAL1 » Fri Apr 01, 2011 11:39 am

Since I just got the Springfield SAR-8, I wanted to hear Springfields "official" position on this discussion.
I got the following email today from them:

Springfield Armory - Recommended ammo for our rifles chambered in .308****SAR’S TOO
Any commercially produced, new in box .308 ammunition that meets the following requirements:
• Is a 147 to 180 grain bullet.
• Is full metal jacket (FMJ), hollow point (HP or BTHP), or ballistic tip type bullet.
• Hornady’s new superformance ammo is OK to shoot in the M1A but NOT recommended for the M1 Garand.
• Hornady tap ammo is better for the shorter barreled rifles.
• Black Hills re-manufactured ammo is ok to use.

You can also use SURPLUS 7.62X51 NATO ammo that meets the following requirements:
• Is clean and from sealed containers
• Is NATO spec. It will have a NATO spec mark on the case head and /or on the packaging that looks like a plus sign inside of a circle.

Ammunition NOT recommended for your rifle:
• Avoid using surplus ammo tha tis “loose” or “bulk” – is is inconsitant in size and can be reloads.
• Avoid using steel case ammo, it is VERY hard on your chamber and can reduce the life span of your rifle.
• Do not use “ light Magnum” type ammo.
• Do not use soft point (SP) ammo, the lead shavings can get into the action and jam it up.
• We do not recommend the use of any cast bullets.

For best accuracy we recommend:
• Federal Match or Black Hills match 168 or 175 grain
• Hornady Match/ custom 168 grain or Hornady TAP 110 or 168 grain.

Please visit web site: http://en.wikipedia.org/wiki/.308_Winchester" onclick="window.open(this.href);return false;
for further comparison between .308 and 7.62 ammo.
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