Author Topic: 7.62 NATO vs. 308 Winchester (Read 1738 times)

Crudders32 · « **on:** September 17, 2005, 03:04:31 PM »

My grandpa has a Winchester Model 88, hammerless lever action rifle in .308 winchester. I have a bunch of 7.62 NATO surplus ammo and was wondering if I could use it in this rifle for target shooting. Thanks.

Dave in WV · « **Reply #1 on:** September 18, 2005, 04:38:00 AM »

If it chambers and extracts ok I'd shoot it. The 7.62 and the .308 have different specs as min and max dimensions. Some times they work and others they won't.

Badnews Bob · « **Reply #2 on:** September 18, 2005, 04:42:15 AM »

Idon't think I'd use it in a lever gun NATO rounds are genrally a higher pressure round. Alot of rifle makers don't recommend shooting MIL SURP in sporting rifles.

pastorp · « **Reply #3 on:** September 19, 2005, 12:07:56 PM »

Badnews I thought nato rounds were a little lower pressure. My m1A1 SA recommends nato rounds.

I have been a .308 win fan for years and fired thousands of rounds of military surplus amo in several browning BLR's in 308. as well as several bolt guns. The military ball I always thought was the same dimensions as comerical .308. The difference was in the primers.

I also shoot surplus ball amo in my mini-14, bushmaster, and CZ527 in 223. My personal opinion is that you can safely fire these rounds interchangably. THERE IS NO difference that would make it unsafe to fire either. IMHO Regards, Byron

Lawdog · « **Reply #4 on:** September 19, 2005, 02:52:39 PM »

Quote from: Crudders32

My grandpa has a Winchester Model 88, hammerless lever action rifle in .308 winchester. I have a bunch of 7.62 NATO surplus ammo and was wondering if I could use it in this rifle for target shooting. Thanks.

I see no problem if it chambers ok. Military ammo is usually ofa somewhat lower pressure so it could be used world wide without pressure problems. Lawdog

Dave in WV · « **Reply #5 on:** September 19, 2005, 03:54:45 PM »

If the ammo is Nato spec it will have a small circle with what looks like cross hairs on the head stamp. If so it should have safe pressure. If it doesn't it may be machinegun ammo and have too much pressure.

Badnews Bob · « **Reply #6 on:** September 20, 2005, 11:35:17 AM »

The powder charge maybe lower but the cases are thicker, Less internal space equals higher pressures. Just because it will work dosn't mean we should do it.

Val · « **Reply #7 on:** September 22, 2005, 01:08:20 PM »

I've always been told that shooting NATO rounds in modern rifles is not a problem. However, game loads in military rifles could have a pressure problem. Anyone have any info on this issue?

Idaho_Hick · « **Reply #8 on:** September 22, 2005, 01:21:12 PM »

Val, the only military rifle one needs to be careful with hunting loads that I know of is the M1 Garand. I have been told by several sources that the gas system was designed exclusively for powders in the IMR 4895 to IMR 4064 range. If I am not mistaken, 4895 was the powder the rifle was designed around. Using slower or faster powders can cause problems.
I'm sure there are probably other finicky early semi-autos, but this is the only one I know of.

BattleRifleG3 · « **Reply #9 on:** December 05, 2005, 09:44:05 PM »

7.62x51mm NATO IS of lower pressure than 308 Winchester. 223 Rem vs 5.56x45mm NATO is where the reverse is true, the military round is hotter.

Which military guns can take full power 308 Winchester is a tough question to answer. In some cases it's an educated guess, but there are real answers. Thicker brass in military ammo means more friction on chamber walls without brass stretching, meaning less rearward thrust on the bolt.

G3s should only be used with NATO ammo, although they are marked 308 by US assemblers. Their recoil operated action would be sensitive to these pressures though and the reduced frictional resistance is a big deal. I previously used 308 ammo in my G3 and the recoil was immensely higher - that would be the bolt slamming way too hard.

FALs were only designed for NATO ammo, but the availability of US made ones with no warnings suggests that using 308 ammo is ok, but adjusting the gas system is a must.

The M1As are advertised by a US company as being able to take 308 Winchester ammo, so I doubt there's any problem. Wear may be a different story.

The Saiga-308s have a distinctly different three lug bolt from the two lug bolts of other 7.62 NATO AKs. I believe they were designed for 308 Winchester if they were aimed at the US sporting market. AK margins most likely allow equally good operation using 308 or 7.62 Nato ammo.

Here's where there may be a problem - The small ring Mausers were designed for much lower pressures than the large ring Mausers. Some of these were converted to 7.62 NATO after it was standardized. These include the La Guardia Mauser and the FR7. There are others I don't know of, but 7.62 NATO small ring Mausers aren't the safest bet with 7.62 NATO ammo. The FR-8, however, is built on the 98 Mauser action which is certainly strong enough for full power standard rim rounds, of which 308 Winchester is one.

In short, anything chambered for 308 Winchester can safely take 7.62x51mm NATO, but not always the other way around (usually though). Anything chambered for 5.56x45mm NATO can use 223 Remington ammunition, but not the other way around. This is actually an issue more often as 5.56 rounds may not chamber in a 223 barrel.

cma g21 · « **Reply #10 on:** December 06, 2005, 02:43:42 PM »

308 Winchester (SAAMI)
Gauges:
GO - 1.6300" NOGO - 1.6340" FIELD - 1.6380"
Maximum Pressure - 62,000 psi
Maximum Proof Pressure - 89,000 psi

7.62 NATO
Gauges:
GO - 1.6350" NOGO - 1.6405" FIELD - 1.6455"
Maximum Pressure - 50,000 psi
Proof pressure - 67,500 psi

http://www3.sympatico.ca/shooters/7_62vs308.htm

http://www.thegunzone.com/30cal.html

Dirigo · « **Reply #11 on:** December 06, 2005, 02:58:20 PM »

also Indian Surplus should never be used.

Kmrere42 · « **Reply #12 on:** December 11, 2005, 06:00:58 AM »

cma g21 Are you sure about the nato spec?? That figure looks to be the C U P figure.

PSI and the cup are a little different. Specs that I have seen are

308 win --- 52,000 CUP

7.62 NATO -- 50,000 CUP

Anyone have the formula to calculate the difference between CUP and PSI.

Paul

cma g21 · « **Reply #13 on:** December 11, 2005, 10:07:49 AM »

Quote from: Kmrere42

cma g21 Are you sure about the nato spec?? That figure looks to be the C U P figure.
Paul

According to links in my post above, both are PSI.

Also see:

http://www.rebooty.com/~dutchman/1895Chile.html

Kmrere42 · « **Reply #14 on:** December 18, 2005, 02:22:07 AM »

Hmm..

Been doing a little research, If the pressure levels are accurate then there should be a very large difference in velocity between the two cartridges. Having fired the 7.62 nato in match settings and have chronographed the same, There was no real difference between the two. I believe the real difference is in the chamber and its allowable wear and possibly the 2k CUP diffence in pressure.

A 12,000 PSI difference in pressure would extrapolate to about 200- 400 fps difference in velocity.

Paul

cma g21 · « **Reply #15 on:** December 18, 2005, 01:03:31 PM »

Quote from: Kmrere42

Hmm..

Been doing a little research, If the pressure levels are accurate then there should be a very large difference in velocity between the two cartridges. Having fired the 7.62 nato in match settings and have chronographed the same, There was no real difference between the two. I believe the real difference is in the chamber and its allowable wear and possibly the 2k CUP diffence in pressure.

A 12,000 PSI difference in pressure would extrapolate to about 200- 400 fps difference in velocity.

Paul

That seems logical. But they also stated that the pressures listed were maximum, and that most .308 was not loaded to maximun pressure.

1911crazy · « **Reply #16 on:** January 14, 2006, 06:02:50 AM »

Make a note of this; The military rifles that say use "nato" ammo only its because the nato case wall is thicker so they won't crack in "Fluted" chambers so one must becareful what ammo is used in what military rifle. The thinner case walls have been noted to crack and blow thru in fluted chambers. My Cetme has a fluted chamber so this means if your going to use it for hunting with soft point ammo you need to reload the nato cases that are boxer primed after cutting the crimp on the edge of the primer pocket. If your shooting a military gun check the chamber first before switching to 308win ammo if its fluted you must use "Nato" ammo only. :eek: A while back there was a rash of Cetme's blowing up I wonder if this was the problem? A split case in a fluted chamber could make life interesting now couldn't it? Whats the breech pressure? 52,000? Its like tossing a gernade with no pin to each other do you feel lucky? Its not worth being cheap or looking for short cuts sometimes we must do it right. Please be safe!!!!!

WARNING: Do not shoot Indian made 308 ammo the charge has been known to be over loaded and all different with the lot. This isn't good stuff if you have it I would take it apart and check and reset the charge then shoot it. I wouldn't shoot it fluted chambers its been known to crack and split too. Do not take a chance and shoot it without checking it out first the results could be hazardous to your health.

1911crazy · « **Reply #17 on:** January 14, 2006, 06:30:38 AM »

Quote from: Idaho_Hick

Val, the only military rifle one needs to be careful with hunting loads that I know of is the M1 Garand. I have been told by several sources that the gas system was designed exclusively for powders in the IMR 4895 to IMR 4064 range. If I am not mistaken, 4895 was the powder the rifle was designed around. Using slower or faster powders can cause problems.
I'm sure there are probably other finicky early semi-autos, but this is the only one I know of.

Your right the IMR4895 is recomended for reloading for all military semi-auto's. The problems is with the burning rates of the powder and the cycle timing of the semi-auto. In a non adjustable gas system the fired case can be extracted too soon while the hot high beech pressure is still present and it blows back on the shooter and sometimes can blow thru the mag well destroying everything in its path. This can also make a bad day at the range too. I use nothing but IMR4895 in all my military semi-auto's with CCI#34 NATO primers they are made for military semi-auto's so slam ires won't occur because they have a thicker wall. The military semi's have floating firing pins and the regular primers have thinner walls so the military semi's can slam fire at anytime when the wrong primers are used.

1911crazy · « **Reply #18 on:** January 14, 2006, 07:04:27 AM »

Quote from: cma g21

Quote from: Kmrere42
cma g21 Are you sure about the nato spec?? That figure looks to be the C U P figure.
Paul

According to links in my post above, both are PSI.

Also see:

http://www.rebooty.com/~dutchman/1895Chile.html

I believe there is a mix up with what the dealers have labeled this mauser its not a 308nato mauser it was made for the 308 cetme round its a lot lower in pressure. It ok and safe to shoot the chilean '95 308 mauser if we use the lower reloading specs of the 308win round.

bigshooz · « **Reply #19 on:** January 14, 2006, 01:10:55 PM »

Just read an article today,and someone who works at fulton armory stated that 7.62 works fine in .308 but not vice versa..308 rounds are a hair to long for proper lockup in 7.62 chambers.so i would say use it up.

Quote

:grin:

PaulS · « **Reply #20 on:** January 14, 2006, 10:00:51 PM »

If you were to chamber a 7.62 NATO round that was at maximum length in a standard or minimum 308 Win. chamber you could have catrastrophic pressure failures due to the round binding the bullet in the case because of the long round and short chamber.
If you are reloading the cases, they are being sized to and trimmed to 308 specs and should not present any problems as long as you remember to reduce the charge for the smaller capacity NATO cases (thicker brass means less internal volume).

Big Paulie · « **Reply #21 on:** January 17, 2006, 12:39:42 PM »

Dear Folks,

T he SAAMI pressure for the .308 Winchester is now 66,000 psi. This is WAY higher than for the 7.62 Nato. One person responded that he didn't think the difference could be too much, as this would translate into a 200 to 400 fps difference in bullet velocity. Unfortunately, this is not how it works. You can't extrapolate velocity in a linear fashion on the basis of chamber pressure.

By way of example, if you underload a shell with too little powder, the pressure will spike way up, and you can have a chamber failure. But this doesn't mean that the bullet, if it gets out of the barrel, is going to be travelling any faster.

The 7.62 Nato and .308 Winchester have different thicknesses in the brass, and this changes the pressure dynamics as well. Why does the .308 Win have greater pressures? It was specifically designed a hunting round. Thinner brass means that it can hold more powder.

Big Paulie