7.62x51 versus 308 Debate

[ffuries]

We always see the 7.62x51 versus 308 debate when it comes to the Spanish M1916 Mausers. Some say they can't take 308 some same they can, some say they can't 7.62x51 some say they can. Some say the ammo is the same thing some say it's not.

Look at the following picture, it will cause some people's heads to explode that is for sure. The head stamp read 7.62x51 308 HP..........So does this prove they are one in the same, OMG the horror.......

[Junk Yard Dog]

That debate goes on with the Indian 7.62mm Enfields as well. I was told .308 was slightly hotter, don't care as I never had any .308 anyway, just surplus 7.62x51mm.

[Lavitias]

I mean .308 is slightly hotter when commercially loaded by about 4,000 psi but seeing as 7.62 rifles are probably proof tested much higher then that I'd think that would be a none issue. I always thought the real issue was actually case thickeness along with head space .308 being 1.630 to 1.6340 and 7.62 nato being 1.6355 to 1.6405. Which would seem more of know your rifle and it's headspace more then anything. Also Saami doesn't even list it as a don't shoot this in this on it's unsafe combinations book but it does take the time to say don't shoot 5.56 out of .223. So with most things I'd say know your rifle and look for the signs of hey this is a bad idea when shooting it.

https://saami.org/wp-content/uploads/20 ... 4-2020.pdf

[SA1911a1]

One thing about the internet, you can find information to prove or disprove any supposition. You can find claims that he Jews are using spaced lasers to burn California. (Although I can not imagine why)

My opinion is one of many. I am not a firearms engineer. I am an evidence based believer, show me multiple cases of them having blown up in folks faces, from factory loaded ammo, and I might change my mind. Sarco sold a boatload of those rifles, marked them .308, had them tested to destruction by independent labs. Had it been a real issue in this country Sarco would have been sued out of existence instead of dying a natural death.

Moses and Gershom argued for 40 days and 40 nights over the ability of Spanish Mausers to shoot .308, and never came to an agreement. Americans have been having the same argument for 40 years. I shoot commercial and surplus in mine, I have had no problems. There are some differences in .308 and 7.62, but not enough to preclude the ability of a rifle, that is safe to fire one, to fire either. As with any used rifle, it is imperative that it is found to be safe to shoot before pulling the trigger an there are reasonable procedures to accomplish that.

Here is a well written and documented opinion on the issue that claims that the reason you should not fire a .308 in a military rifle is about headspace, not pressure at all....


http://www.how-i-did-it.org/762vs308/chamber.html

[Brake Weight]

I did some digging in the past on the matter. 7.62x51 is similar to the 5.56 as it’s a NATO round, or a military version. Early on the .308w was used but the manufacturer of 7.62x51 won the contract. A weapon chambered in either ‘NATO’ round has a looser chamber than the .308w or .223 counterparts. This was by design so that mass produced military rounds could have some variance in powder and when crimping/pressing a bullet into the cartridge. When you are full auto machine gunning the enemy you don’t want your gun to jam.

That’s what I found online anyway. But any decent branded ammo would go either way. I shoot .308w and 7.62 from my .308w bolt action and no issues. I would never shoot milsurp 7.62x51 in it though.

[WeldonHunter]

Many years ago (like 10) I did extensive research about this when my uncle gave me a Garand that had been rebarreled by Arlington Ordnance with a 7.62x51 NATO stamped barrel. I read the debate about.223 vs 5.56 and saw that Sammi had a listing for those and not to use 5.56 in a .223 chamber but nothing about .308 vs 7.62x51. I had ordered 1000rds of .308 thinking it was the same because I was new to this and just started running gun-deals and saw they were listed as inter-changeable on most vendor's sites. After doing further research and coming up with nothing definitive I decided to go with what the barrel had stamped on it which is 7.62x51 NATO and bought a crapload of it. I still have the 1000rds of .308 and have since bought an AR10 that I can use that in so it wasn't a wash. Point is I never found anything one way or the other as to what's safe and what isn't. I saw some competition shooters say "you're taking your life in your hands swapping them" and some said "It's no problem, been swapping them for years" and the same can be said in general from most other sources.

[Junk Yard Dog]

The M1 is built to handle the pressures of the .30-06, same barrel with shorter chamber for .7.62x51, or .308. .308 should be no problem for anything made for .30-06. Worst problem I can think of would be having to install the adjustable gas plug to regulate the gas pressure. The M1 gas system is regulated for USM2 ball, anything else will require adjustments be made of the rifle will short stroke, or start battering itself to death.

[Lavitias]

Many years ago (like 10) I did extensive research about this when my uncle gave me a Garand that had been rebarreled by Arlington Ordnance with a 7.62x51 NATO stamped barrel. I read the debate about.223 vs 5.56 and saw that Sammi had a listing for those and not to use 5.56 in a .223 chamber but nothing about .308 vs 7.62x51. I had ordered 1000rds of .308 thinking it was the same because I was new to this and just started running gun-deals and saw they were listed as inter-changeable on most vendor's sites. After doing further research and coming up with nothing definitive I decided to go with what the barrel had stamped on it which is 7.62x51 NATO and bought a crapload of it. I still have the 1000rds of .308 and have since bought an AR10 that I can use that in so it wasn't a wash. Point is I never found anything one way or the other as to what's safe and what isn't. I saw some competition shooters say "you're taking your life in your hands swapping them" and some said "It's no problem, been swapping them for years" and the same can be said in general from most other sources.

The first sounds like a CYA answer so you can't call a lawyer if you blow your gun up. The second actually sounds pretty realistic.

[steelbuttplate]

It's best to use the round stamped on the rifle. My Springfield manual say no .308 Win thru the M1A, 7.62 Nato only. The Russian Tula bolt action I have has both stamped on it. You should use M 80 only in those Spanish conversions.

[Longcolt44]

I guess I did, "Trial by fire", I shot my Spanish Mauser with 7.62X51 way back before you could read it was okay.

[Junk Yard Dog]

It's best to use the round stamped on the rifle. My Springfield manual say no .308 Win thru the M1A, 7.62 Nato only. The Russian Tula bolt action I have has both stamped on it. You should use M 80 only in those Spanish conversions.

The Egyptian Hakim can shoot any 8mm round you find despite the small variations in pressure between different manufacture cartridges. The reason for this is it has an adjustable gas system, you can set it for the round you are using so it won't batter the bolt to death, you just can't use mixed rounds at one time. Uncle Sam intended the M1, M1 carbine, M14, M16 to use only the ammunition Uncle Sam provided and no other. These rounds, like the M2 ball for the M1, were made to very specific spec, and these rifles have no provision for gas adjustment unless aftermarket gas cylinder plugs are added. The M14 will shoot .308, but without being able to adjust the gas system to the slightly increased pressures you will start battering the op rod, and bolt. Uncle Sam's M14's could take it for a little while, so can most civilian ones using GI parts kits and USA receivers, but don't try it with the Chinese copy as they are known for soft metal. The bolt rifles of course have no gas system to worry about, here you are just worried about the hardness of the steel, how many rounds fired at pressure past original design spec can it take before parts start to deform and headspace slowly increases. Maybe never, maybe soon.

[bogozzo]

Actual cartridge sizing/naming aside, not all ammo is created equal. Following the "wise advice from the internet" that its ok to use 7.62 in a commercial 308 I ordered 500 rounds of steel case Chinese surplus when I got my Savage 99 in 308. The issue with this particular 7.62 is that its designed for machine guns and the casing is thin enough that it expands and locks itself in the chamber of my 99. About half of the rounds will eject when the gun cools, a quarter eject fine but the last quarter need to be tapped out from the muzzle (fiberglass cleaning rod) whether or not the gun has cooled. In my son's Savage Axis they eject fine for every shot, but the primers are hard strike and about half of them need a second hit to go bang, an issue that occurs about 1 in 10 in my older Savage. Both guns run well with commercial brass cartridges and even Baurnal steel case (the cheapest commercial round I can find here).

I think that the engineering in a rifle's chamber and barrel is such that they will withstand pressure differences without catastrophic failure, but damage to the firearm can occur in other ways (say a broken ejector in my gun, damage to firing pin in my son's). So, end to the long story? My son has about 400 rounds to play with, knowing how the ammo will perform.

[Lavitias]

Actual cartridge sizing/naming aside, not all ammo is created equal. Following the "wise advice from the internet" that its ok to use 7.62 in a commercial 308 I ordered 500 rounds of steel case Chinese surplus when I got my Savage 99 in 308. The issue with this particular 7.62 is that its designed for machine guns and the casing is thin enough that it expands and locks itself in the chamber of my 99. About half of the rounds will eject when the gun cools, a quarter eject fine but the last quarter need to be tapped out from the muzzle (fiberglass cleaning rod) whether or not the gun has cooled. In my son's Savage Axis they eject fine for every shot, but the primers are hard strike and about half of them need a second hit to go bang, an issue that occurs about 1 in 10 in my older Savage. Both guns run well with commercial brass cartridges and even Baurnal steel case (the cheapest commercial round I can find here).

I think that the engineering in a rifle's chamber and barrel is such that they will withstand pressure differences without catastrophic failure, but damage to the firearm can occur in other ways (say a broken ejector in my gun, damage to firing pin in my son's). So, end to the long story? My son has about 400 rounds to play with, knowing how the ammo will perform.

This is probably more a case of cheap Chinese surplus coming back to haunt you it's cheap for a reason after all. I've shot cheap Chinese .223 and ya wasn't a great idea as I had some bullets actually come unseated while trying to feed. Like with most things you get what you pay for there. That being said sounds like your son has some cheap plinking ammo at least for his gun.

[bogozzo]

This is probably more a case of cheap Chinese surplus coming back to haunt you it's cheap for a reason after all. I've shot cheap Chinese .223 and ya wasn't a great idea as I had some bullets actually come unseated while trying to feed. Like with most things you get what you pay for there. That being said sounds like your son has some cheap plinking ammo at least for his gun.
[/quote]

Absolutely. The joy of the "deal" I got fell away real quick as I was sitting at the range with a jammed gun and 2 live rounds left in its internal magazine. I've seen some ammo from the same batch at auction since .. I'm presuming someone dumping it because of similar experiences.