Is there a difference between .308 Win and 7.62 x 51 NATO?


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toejamm
March 12, 2011, 04:35 PM
I am aware of the differences between .223 Remington and 5.56 x 45 NATO.
I have always wondered what, if any differences there are between .308 Winchester and the NATO 7.62 x 51mm round.

Anyone.......?

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Edited 3/14/11 Monday:
Thanks for the help guys. I found out exactly what I wanted to know.
Next time I'll check the previous threads before posting a question like this.
Thanks again........................

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Flatbush Harry
March 12, 2011, 04:39 PM
There are...and, if you use the search function, various threads will explain them.

Cheers,

FH

toejamm
March 12, 2011, 05:15 PM
Thanks Harry,
It seems as though this topic has plenty of past threads. Looks like I'll be doing some light reading.

My main reason for asking is because I shoot both from my AR-10 and M1A and they operate without a hitch. A buddy has a Rem. 700 chambered in .308 he is looking to sell and I was curious as to the nuances between the two rounds.

Onmilo
March 12, 2011, 05:24 PM
Depending on the model of Remington 700 it may or may not have 7.62X51 chamber dimensions.
Sporting type rifles will have .308 commercial chambers and Tactical rifles can have either.

If the chamber is commercial dimensioned, it isn't a big thing to have a gunsmith recut the chamber to NATO 7.62X51 dimensions. HTH

LKB3rd
March 12, 2011, 05:30 PM
I thought it was the opposite from .223/ 5.45, where .308 is higher pressure than 7.62 x 51.

W L Johnson
March 12, 2011, 05:59 PM
I thought it was the opposite from .223/ 5.45, where .308 is higher pressure than 7.62 x 51.
Same pressure, both 62,000 psi. You may find websites where 7.62x51 is stated to be 50,000 psi, it's not. It's 50,000 CUP (copper units of pressure). People keep changing cup to psi without converting and then declare that 308 will blown up a 7.61 NATO gun. When they were tested two different methods were used, that's why the two different units. It's just like inch vs centimeters.

Onmilo
March 12, 2011, 06:49 PM
A lot of folks don't understand that NATO specification brass is thicker than commercial .308 which means less case capacity and you cannot handload NATO brass to the same maximums that you can with commercial brass.
Using maximum loads of powder in the thicker NATO cases can raise pressures substantially.

Some commercial .308 is loaded to maximum and somewhat obscene levels of power and pressure.
They normally carry monikers such as "Light Magnum" or "Extreme Performance", avoid them in military type semi automatic rifles to stay on the safe side.
These types of cartridges are designed to operate with best results in bolt action and strong single shot actions and even in these modern rifles I think this type of ammunition wears actions and parts excessively and quickly.

Robert
March 12, 2011, 06:53 PM
There are literally hundreds of threads on this topic.

The short answer is there is almost no difference. Yes NATO brass tends to be a bit thicker and the dimensions are .0000001 different, bit of sarcasm, in some areas. But for all intents and purposes of the average shooter 308 is 7.62x51 is 308.

Onmilo
March 12, 2011, 06:57 PM
Right up until you start reloading the stuff,,,,

Geno
March 12, 2011, 07:02 PM
My Remington M700 SPS Tactical in .308 Win fired the 7.62 ball ammo extremely accurately. Fortunate for me, because it really reduced the cost of plinking.

Geno

W L Johnson
March 12, 2011, 08:12 PM
Per NATO docs, 7.62 NATO (7.62x51) spec chambers are proofed to 75,000 psi. 62,000 is still way below that. It's the head space difference that may cause problems if your head space is borderline one way or the other.
This explains it better that I can
http://home.comcast.net/~ehorton/The%20Truth%20About%20308%20Win%20and%20762%20NATO.pdf

snake284
March 12, 2011, 08:18 PM
I have read that CUP was used in the days before they had good pressure measuring instruments. I think they put a piece of soft lead between the bolt face and the cartridge base, shoot the rifle and mic the thickness of the lead. I really don't know how they arrive at teh CUP from this, but they do. Now days most just use PSI since they can actually measure it.

Edited to Add:

The 308, if anything has higher pressure potential than its military counter part. This is opposite of the 5.56 x 45 Nato, or .223 Remington. This is the one you have to be careful with.
Onmilo pegged it correctly. The military brass is thicker.

USSR
March 12, 2011, 08:43 PM
The 308, if anything has higher pressure potential than its military counter part. This is opposite of the 5.56 x 45 Nato, or .223 Remington. This is the one you have to be careful with.
Onmilo pegged it correctly. The military brass is thicker.

There is no higher pressure potential, you just use a couple less grains with most milsurp brass to generate the same pressure as most .308 brass. You do the very same thing when using Lapua brass, which is heavy commercial brass, as opposed to Winchester brass, which is very light.

Don

40nascar
March 13, 2011, 01:53 AM
The .308 has a commercial headstamp, the 7.62 has a military headstamp and thicker brass for use in machine guns. Outer dimensions for all practicle purposes is identical. You can use either in your gun. If you don't handload, just shoot whatever commercial or military you choose. If you handload, reduce the powdercharge at least 2 grains with the military brass. Thats all folks.

SwampWolf
March 13, 2011, 04:53 PM
Thats all folks.

You've summarized it well, 40nascar. Can't disagree nor add one thing to what you've said.

USSR
March 13, 2011, 05:34 PM
Now, someone PLEASE make this a sticky, so we don't have to rehash this over and over again.:banghead:

Don

mshootnit
March 13, 2011, 07:02 PM
Also the same holds true for 5.56. If you are reloading military 5.56 brass and shooting in a 223 reduce your charges somewhat or at least pay very close attention when approaching max loads.

Balrog
March 13, 2011, 07:43 PM
Now, someone PLEASE make this a sticky, so we don't have to rehash this over and over again.

Yes I am tired of being forced to read these threads against my will.

Oh wait, I guess I could just skip the thread, couldn't I?

ball3006
March 13, 2011, 11:58 PM
If people reloaded for maximum accuracy instead of maximum velocity, this discussion would not be happening. I have been reloading 308 and nato for 40 some years and never have I seen any problems with pressure or otherwise. I just segrigate my commercial and military brass and load according to the manuals....chris3

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