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.308 Winchester VS 7.62X51mm NATO

rogers0311

Sergeant
Full Member
Minuteman
Oct 27, 2007
158
2
38
Camp Lejeune and elsewhere
Guys,

Correct me if I am wrong but as I understand it, there are very slight differences between the .308 Winchester and 7.62 mm NATO rounds. I believe the headspace is slightly different, and 7.62 NATO will give you chamber pressure of about 50,000 psi whereas .308 will give you either 62,000 psi or 67,000 psi (cant remember exactly which).

Has anyone shot both out of their rifles and if so, can you notice any differences in performance?
 
Re: .308 Winchester VS 7.62X51mm NATO

the 7.62 nato has 62.000 pso of pressure , the 308 has 50.000 ... and the chamber of case of 7,62 is 0,33 mm longer than 308
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Re: .308 Winchester VS 7.62X51mm NATO

Im woundering about the same thing as I have a AIAW on it´s way to me. Can I load as usual with mu 308 dies or do I have to get 7.62 Nato dies and fireform 308 brass to be on the safe side?

Edit: Got answer from AI and it´s OK to use 308 Win in the AIAW
 
Re: .308 Winchester VS 7.62X51mm NATO

This has never been talked about here before. Just kidding. It comes up frequently.

First off SAS_Sniper is incorrect and rogers0311 is right; the .308 SAAMI specs state 62,000PSI. Now the 6mmbr.com website does talk about the differences between the two and says the NATO round is loaded to 50,000 PSI and that rifles made for 7.65X51 NATO should not use full power commercial .308 ammo. They even link to some other sites with analysis on the subject.

All that being said, I was informed here the last time I saw this type of discussion, that the 6mmbr.com information was incorrect and misleading. It seems that 7.62X51 NATO is loaded to 50,000 CUP, not PSI and these are different units and not-interchangeable. The poster went on to discuss and infirm several others issues that 6mmbr.com was mentioning. I invited the poster to correct 6mmbr.com. I checked just now and the information is as it was before.

I looked in loading manuals that make a difference between the two loads and indeed the loads listed for 7.62X51 NATO are milder than the .308 Winchester loads. So who is one to believe?

The 6mmbr.com website also mentions the difference in headspace but states that 7.62NATO is usually loaded so that it will headspace properly in SAAMI .308.

In light of this contradictory information, I handload my .308 using .308 Winchester recipes and I shoot 7.62 NATO ammo out of by last remaining 7.62NATO chambered rifle.

The brass for 7.62X51 NATO is thicker than the commercial .308 so adjust you load accordingly, but it will resize nicely in .308 dies.
 
Re: .308 Winchester VS 7.62X51mm NATO

As I said, there is contradictory information out there.

The SAAMI spec that you show only covers SAMMI cartridges, it does not cover military cartridges. You will notice that when they discuss the .223 Remington, they warn about using "5.56mm Military." As I said, none of the listed cartridges on the left are military. SAAMI does not have a say over the military loadings and it would be unwise for them to list them on the left hand side. Or at least that is my understanding.

Wikipedia is not what I would consider a reliable source of information.
 
Re: .308 Winchester VS 7.62X51mm NATO

Sig, I think SAAMI would at least mention this alleged 12,000 psi difference in the most popular round in the USA... they do it with the 5.56 which is military
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I agree with you on wikipedia, in general, but all you have to do in this case is follow the citations at the bottom of the page, this link on the wikipedia article is from the UK defense standarization home page:

http://www.dstan.mod.uk/data/05/101/01000100.pdf

check page 19, hope this settles it.

 
Re: .308 Winchester VS 7.62X51mm NATO

Also remember that even if chamber pressure is aprox. the same in 308 Win vs 7.62 NATO, the pressure curve may be different due to different bullet weights and different powders used compared to the NATO M80 load (about 147 gr @ 2800 fps in a 22" barrel). In military gas guns the port pressure can be different resulting in increased impulse on the moving parts and reliability/durability problems.
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rogers0311</div><div class="ubbcode-body">Guys,

Correct me if I am wrong but as I understand it, there are very slight differences between the .308 Winchester and 7.62 mm NATO rounds. I believe the headspace is slightly different, and 7.62 NATO will give you chamber pressure of about 50,000 psi whereas .308 will give you either 62,000 psi or 67,000 psi (cant remember exactly which).

<span style="font-weight: bold">Has anyone shot both out of their rifles and if so, can you notice any differences in performance?</span> </div></div>




i have shot some winchester and some nato ammo this last friday... I would recommend the commercial loads for .308 caliber rifles. the nato rounds jumped around alot for me. then again i have a 1:10 rate barrel and if the nato rounds are 145 gr that might be a reason based on the lilja twist rate chart. for me the nato stuff was everywhere on the paper compared to the commercial stuff. thats my tests and two cents.
smile.gif


 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Sig, I think SAAMI would at least mention this alleged 12,000 psi difference in the most popular round in the USA... they do it with the 5.56 which is military
wink.gif


I agree with you on wikipedia, in general, but all you have to do in this case is follow the citations at the bottom of the page, this link on the wikipedia article is from the UK defense standarization home page:

http://www.dstan.mod.uk/data/05/101/01000100.pdf

check page 19, hope this settles it.

</div></div>

They do not mention it, because it's safe to shoot 7.62 NATO in a commercial .308 rifle; everyone knows that and nobody is questioning it. What I am saying is that SAAMI is not going to say that 7.62NATO chambered rifles are unsafe to use with commercial .308 ammo; it is not their purview.

And I'm going to believe some trash pdf on a UK website? That's even more unreliable than Wikipedia.
 
Re: .308 Winchester VS 7.62X51mm NATO

5.56 or .223?

Same diff.
Are you finding, buying, or loading?(Don't forget using)
7.62 seems to always go bang.

What kind of velocity spikes have you guy's seen with the Winchester 5.56?
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TCA4570</div><div class="ubbcode-body">5.56 or .223?

Same diff.
Are you finding, buying, or loading?(Don't forget using)
7.62 seems to always go bang.

What kind of velocity spikes have you guy's seen with the Winchester 5.56? </div></div>

are you asking if the 5.56 is the same as .223 ? if you are the answer is no... the 5.56 has more pressure and is not recommened for use in .223 chambered barrels. AR's for example have the wylde chamber that will work with both of the rounds.
 
Re: .308 Winchester VS 7.62X51mm NATO

I think where the "myth" lies is the different methods (Copper Crusher/Electronic Transducer/etc.), units (CUP/PSI/BAR/etc.), what (MAP/Peak/Working/etc.) and locations of the sensors (mid-chamber/shoulder/etc.) in reading the pressure during testing between SAAMI and NATO. I understand that CIP and SAAMI just test for pressure while NATO STANAG requires far more testing for interoperability etc.

At least that's how I understand the pressure issue.

I was present and immediately adjacent to a kaboom of MY
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issued DRMO M14 while it was being fired semi-automatic, with commercial SAAMI spec 180gr SP ammunition instead of the M80 ball I'd supplied for the purpose. Blew out the magazine follower/spring and floorplate, the extractor, the stock at the receiver/magazine well, the operating rod out of its channel and jammed the bolt halfway back
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, and BTW scared the snot out of the LE intern
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who was firing it as well as the "Instructor"
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who was running that demo lane and unknown to me, dragged that SAAMI ammo out of the locker when the ball I’d supplied began to run low.

I turned the rifle in to our Chief Armorer at Headquarters who then brought the rifle to a gunsmith friend of his who'd been a Military and NRA High Power shooter/armorer and when he told him what had happened and showed him the rifle the old armorer looked at him like he had a dick growing out the top of his head and said "Boy you don't ever shoot .308 in an M14 !".

I don't know if it was a soft primer, soft brass, a time/pressure curve issue due to the heavy bullet, an overpressure SAAMI .308 in a 7.62 NATO chamber, or what, I just know I had to do a couple memos and lost the best M14 out of the lot we'd received.

Old wives tail or not, I'll just stick with the "myth" and <span style="font-weight: bold">not</span> run SAAMI .308 Winchester in a 7.62X51 NATO chamber
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at least in semi-automatics anyway. That, BTW, is exactly opposite of what’s required with the .223/5.56 issue, NO NATO in a .223 chamber.
 
Re: .308 Winchester VS 7.62X51mm NATO

Sig685, "trash pdf on a UK website"?
http://94.236.30.21/index.html
you are joking or hard headed
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subMOA, as said before:

"even if chamber pressure is aprox. the same in 308 Win vs 7.62 NATO, the pressure curve may be different due to different bullet weights and different powders used compared to the NATO M80 load (about 147 gr @ 2800 fps in a 22" barrel). In military gas guns the port pressure can be different resulting in increased impulse on the moving parts and reliability/durability problems."

In particular in the M14 it is a very well known issue. Heavy bullets + slower powders = more gas port pressure for a longer time = beating of the action. In the example you mentioned there must be other factor too.
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Sig685, "trash pdf on a UK website"?
http://94.236.30.21/index.html
you are joking or hard headed
smile.gif
</div></div>

Sorry, my bad. I should have said "rubbish" instead of trash.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">
subMOA, as said before:

"even if chamber pressure is aprox. the same in 308 Win vs 7.62 NATO, the pressure curve may be different due to different bullet weights and different powders used compared to the NATO M80 load (about 147 gr @ 2800 fps in a 22" barrel). In military gas guns the port pressure can be different resulting in increased impulse on the moving parts and reliability/durability problems."

In particular in the M14 it is a very well known issue. Heavy bullets + slower powders = more gas port pressure for a longer time = beating of the action. In the example you mentioned there must be other factor too. </div></div>

Let me see. The M14 is chambered in 7.62 NATO and it blew up when it was fired with commercial .308 ammo. Somehow, I don't think this M14 would have blown up if it had only been used with 7.62 NATO ammo. I'm glad you finally saw the light; better late than never.
 
Re: .308 Winchester VS 7.62X51mm NATO

Commercial 308 Win 150 gr ammo (not the "extra velocity" ones loaded with slower powders) should be fine in any military rifle, as the pressure/time curve is the same.

And in the extreme blow up example subMOA mentioned, I think there were other issues at play. I have fired a M14 and FAL with commercial 175-180 gr 308 Win loads and nothing happened (at least for a few boxes of ammo), come on, I'm sure some other have done the same too...

Anyone that reloads knows that in order to get 2800-2850 fps out of a 22" barrel with a 308 Win, and using the powders commonly used in military 7.62 NATO loadings (ussually 43 to 45 gr) the pressure is about 50,000 CUP or close to 60,000 psi. The military brass is heavier, with a little less internal volume, so in order to get the same performance the pressure will be aproximately the same.

And the UK site is legitimate, sorry if you cannot see it.
 
Re: .308 Winchester VS 7.62X51mm NATO

Just got this from Paul Novak, LE sales and tech questions at Winchester:

"In a 7.62 NATO Chambered rifle you can safely shoot either 308 Winchester or 7.62 NATO. You can also safely shoot the same 2 cartridges in a rifle chambered in 308 Winchester."
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: winxp_man</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TCA4570</div><div class="ubbcode-body">5.56 or .223?

Same diff.
Are you finding, buying, or loading?(Don't forget using)
7.62 seems to always go bang.

What kind of velocity spikes have you guy's seen with the Winchester 5.56? </div></div>

are you asking if the 5.56 is the same as .223 ? if you are the answer is no... the 5.56 has more pressure and is not recommened for use in .223 chambered barrels. AR's for example have the wylde chamber that will work with both of the rounds.</div></div>

Some AR15's have a SAAMI .223 chamber, some have a 5.56 NATO chamber, and some have a Wylde chamber.

Check the barrel stampings (if present) or ask the manufacturer.

You can always shoot SAAMI .223 ammo in a 5.56 NATO chamber, but vice-versa might get you in trouble. Notice I said MIGHT. You can shoot either loading in the Wylde chamber, and it's generally not as "loose" as the NATO chamber so it promises better accuracy.

Using SAAMI .308 ammo or 7.62 NATO ammo in a boltgun is normally alright. Notice I said NORMALLY. However, checking headspace is strongly advised before shooting .308 SAAMI ammo in a gas gun (especially an M1A or other M14 derivative) that's chambered for 7.62 NATO. The details can be pretty involved and long winded, so if you don't want to take my word for it check out the paragraphs devoted to this subject in Kuhnhausen's "The U.S. .30 Caliber Gas Operated Service Rifles, A shop Manual, Volumes I & II", and articles by Clint McKee (Fulton Armory) and Ron Smith (Smith Enterprises) that probably still can be found on their websites.
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Commercial 308 Win 150 gr ammo (not the "extra velocity" ones loaded with slower powders) should be fine in any military rifle, as the pressure/time curve is the same.

(snip)</div></div>

Understood, as long as you shoot commercial .308 ammo that is loaded the same as 7.62 NATO, you will not have a problem. Anything heavier but rare, like 168, 175 and so on, you may have a problem up to and including blowing up your gunn. But that will be your fault.
 
Re: .308 Winchester VS 7.62X51mm NATO

I've found every 7.62x51 Nato chamber I've owned, is huge, vs a .308 win.

I've shot a little M59, M80, NM, Special ball, and everything else ever issued in TRW XM21's an Winchester M14's, to include Red an Yellow box .308 win 180 an 150 gr silvertips we had flown in, an never had issue, nor did anyone else running them.


I wore out 17 barrels on my old NFA H&R M14e2 while running .308 Win from every mfg out there, never had an issue. I've shot up much 180gr Serria Pro Hunters loaded in after burner, plus a few duplex an some tri-plex loads, none ever damaged Uncles shit nor mine. I must live right?

When there is alot of doubt, an dis-information, follow the money, works everytime.

Oh, one other fact, a broken or stuck firing pin will cause an out of battery issue. A weapon thats in battery will bust a barrel at the ring, before blowing out the mag or sticking the bolt.


Edit to add,... The world I live/operate in, may have different laws on mechanical motion, and laws of Physic's than anyone else on this rock. The M14s I've used over the last 45 years could have been just that special, so don't try anything on your own. Always read the internet for the most up todate info there is or ever will be.
Doing your own thinking, and investigating is not the way of the new world order, you have been warned!


 
Re: .308 Winchester VS 7.62X51mm NATO

Gunfighter14e2, you just have a guardian angel sitting on your shoulder everytime you shoot those waaaay overpressure, heavy bullets, thin brass, sensitive primers, commercial 308 rounds in your M14s
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Or could it be an internet myth?? They don't blow up down here in south america too, and believe me we feed them everything we can find/reload.

Seriously, I've read many times that the M21s were having longevity issues with M118 LR, and they lked a little reduced loading, is that true?
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Seriously, I've read many times that the M21s were having longevity issues with M118 LR, and they lked a little reduced loading, is that true? </div></div>

My time was with the XM21 and the for runners of same. That said, I understand (IIRC) the port pressure with M118LR to be the same, as XM's with cans. That system was never built for that mission, ammo. It did it for us(173 grs) w/o issue, but then again we did not use it with Sonics cans for anything other that what it's intended mission was. It filled that roll just fine w/o mech. issues.

Anyone thats ever ran a XM21 w/a can knows the issues that it has. Many tried turning off the spindle valve,... they had to learn for theirselfs.
Most all the loading I've ran over the years, were either IMR 3031 for up to 150 grs or the old standby BL-C(2) for everything up to 180grs, but add a can and you better be looking at something like H-380, hard.

In the mid 60's we were already drilling the gas piston plugs, pistons, barrels an gas cylinder holes(plus timing)to change the ROF on the M14e2's. The XM's were drilled as well if they were, canned. They should be able to do the same with all the high tech wizbang stuff they have now. I'd start by changing the gas system if their beating theirselfs that bad, but then again is it being used for the mission it was built for, or is it just spraying semi auto 7.62 fire around an hopeing?
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Gunfighter14e2, you just have a guardian angel sitting on your shoulder everytime you shoot those waaaay overpressure, heavy bullets, thin brass, sensitive primers, commercial 308 rounds in your M14s
laugh.gif
</div></div>
Obviously my M14 could have used that Guardian Angel that day to help with whatever caused the Kaboom
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A point of interest, since Gunfighter brought it up; The same gunsmith who originally inspected the rifle, and who I understand had an impeccable reputation, advised the agency in writing that he could find nothing mechanically wrong with the rifle. The firing pin must have still been intact, but that obviously doesn't mean it didn't hang-up at the wrong time.

Of further interest; When the ammo manufacturer (I want to say now it was Remington, based upon remembering green/yellow boxes at the scene of the crime
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, but I could have sworn it was Winchester) was sent the ammo in question, they advised, as I remember, they could not find such pressures as could have been the direct cause of the kaboom, but advised not to shoot any more of that partial, about 1/2 case and return it to them. They sent a brand new case of .308 ball as a replacement AND were in negotiations with the agency as far as the repair costs on the rifle. The negotiations dragged on and I lost interest in what happened. I don't know that they did in fact pay for repair of the rifle, but I will see if I can find out, now that this discussion has made me wonder.

Like I mentioned originally, maybe it was a soft primer, soft brass, time pressure curve issues, an overpressure .308 in a 7.62 chamber or as Gunfighter suggested a sticking firing pin, maybe a bit of all of them, hell maybe the way the moon aligned with the stars has something to do with it. I don't know and I don't imagine anyone else can prove the cause of the kaboom.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Or could it be an internet myth?? They don't blow up down here in south america too, and believe me we feed them everything we can find/reload.</div></div>
Doesn't the water in the toilet rotate the opposite direction down there
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. That could explain it
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.

With the Statute of Limitations well past, I'll admit I recall having put a few boxes of FGMM 168 through it from the bench, when I was selecting which of the several available M14s to take as issue. It was zeroed for plain old 147 ball though, commercial SAAMI 147 ball
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.

It is kind of strange that no one has posted any kind of official "Holy shit don't ever do that" kind of warning here. I'm running low on my stash of surplus NATO ball and have a FAL and PTR91 that need to be fed, but am not willing to buy ammo at todays prices...
 
Re: .308 Winchester VS 7.62X51mm NATO

subMOA, given that you are a police officer, I'm sure you can call/write to the ammo makers and ask:

- if the 308 Win/7.62 ammo NATO is loaded at different pressures.
- if there are any recommendation regarding safe interchange of both loads in spite of chambering markings, specifically 308 Win loads in 7.62 NATO marked military gas guns.
- if there is any bullet weigth or a particular load that might cause problems or excessive wear in certain gas guns.

I did yesterday, and got the quick answer I posted above from Winchester. For them is the same.
 
Re: .308 Winchester VS 7.62X51mm NATO

It could have been the primer from the round before, as a in battery weapon will not do that kind of damage.
Case in point, I once took 5, 20rd mags of Uncles high pressure test ammo in a locked down M14 an ran them all in Full Auto, without issue. We then loaded up more, with increasing pressure, an ran them F/A until we split the barrel, front reciever ring, an locked up the gas piston. The weapon was in battery everytime before going bang. The bolt works were toast but the bolt was still in battery after the rupture. The weapon was a real USGI Springfield Armory, not a M1A of the same name.

Point is this, unless there is a bolt part issue, that weapon will not go bang unless it's in battery, do to the safety bridge, that most know nothing about.

If everyone would take the time to do their own leg work on the M14 family, there are many things uncle wanted it to do, from the drawing board. It is not just a M1 Garand remake, many things/ideas came from the BAR as will, if you look close. This could be the reason the old girl is still in service today. It's not a weapon one just picks up an runs correctly in F/A w/o proper training either, an this issue has turned off most who tried it that way an failed.
 
Re: .308 Winchester VS 7.62X51mm NATO

Tiro; Kaboom occurred in the early '90s, retired 9 years ago after 27 years on the Job
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.

Kind of in the same boat as Gunfighter's title line...A never was, has been
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.

Issue wasn't a burning concern, it just became of mild interest as a result of what ya'll were writing on this thread
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Read your Winchester inquiry results, thanks. Not that I disbelieve it at all, in fact I'm on board. But, I worked in the LE industry briefly after retirement, so I look upon such pronouncements from factory reps with a bit of a jaundiced eye. Call Leupold and ask them; 1/4 MOA or 1/4 IPHY
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You know what I mean
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.

Gunfighter; I readily bow to the voice of experience, obviously alot of experience, but the armorer and the ammo company were, not surprisingly, sure pointing fingers at each other at the time
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.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunfighter14e2</div><div class="ubbcode-body"> It's not a weapon one just picks up an runs correctly in F/A w/o proper training either, an this issue has turned off most who tried it that way an failed.
</div></div>
BTW, just for the record and as noted, the Kaboom occurred at semi-automatic, we had no use for automatic fire and the selectors were removed.

I've used plenty of commercial M80 ball equivalent without a second thought as well as various commercial M118 Special Match equivalents occasionally, figuring they were what was intended, but always shied away from anything outside of that. I’ve got no need to use other than those equivalents either, except for about half a case of old .308 Silvertips someone gave me at a school that I think I'll pull from the bottom of a stack and sell or trade for some ball.

Went back and looked at both my posts and see nothing to alter, except where I failed to specify what I meant where I put “not run SAAMI .308 Winchester in a 7.62X51 NATO chamber” instead of what I noted just above regarding equivalent loads. I will fix that oversight after dinner…

Thanks guys, enjoyed the discussion…
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sub2.908cm/100m</div><div class="ubbcode-body"> I’ve got no need to use other than those equivalents either, except for about half a case of old .308 Silvertips someone gave me at a school that I think I'll pull from the bottom of a stack and sell or trade for some ball. </div></div>

I'd be willing to pay the growing rate for you to buy some Ball, if you want to sell any or all of the old Winchester Silvertip? I have no use for the new style Silvertip, but could use the old stuff that came in the Red an Yellow box. Any of the weights, 150, 180, or 200grs works for me.
 
Re: .308 Winchester VS 7.62X51mm NATO

My Fulton Match Grade shoots M118LR really nice, and has no issue with the 150's from Wally World or the local hardware stores. Shoot even that crappy old Indian stuff works nice in it. Fact is, it has digested everything I have put into it(1k plus rounds I think). I am really wondering about all that older mumbo jumbo on reloads and such in it. My reloads that I shoot in my other rifles have plenty of depth in the primer seat, and no slamfires have ever happened. 308? 7.62x51? All works fine so far
 
Re: .308 Winchester VS 7.62X51mm NATO

They always will, that bitch was almost, Note, almost, GI proof. The M14 will run round for round with any AK, in any A/O, but will put them on target 2 times the AK range, with more punch.
 
Re: .308 Winchester VS 7.62X51mm NATO

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sub2.908cm/100m</div><div class="ubbcode-body">
Read your Winchester inquiry results, thanks. Not that I disbelieve it at all, in fact I'm on board. But, I worked in the LE industry briefly after retirement, so I look upon such pronouncements from factory reps with a bit of a jaundiced eye. Call Leupold and ask them; 1/4 MOA or 1/4 IPHY
wink.gif
You know what I mean
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.
</div></div>

subMOA, I understand perfectly, but Paul Nowak answers the tech FAQ at Winchester and I think is far more knowleable and trustworthy than a normal factory rep.

In any case, I just got this from Ron Smith, who I believe knows a thing or two about the M14
wink.gif


"You will not have any trouble with .308 or 7.62 in either a gas gun or bolt, it just isnt enough drifference to matter."
 
Re: .308 Winchester VS 7.62X51mm NATO

Just wanted to add that in addition to Winchester and Ron Smith I have contacted other ammunition manufactorers: Norma, Lapua, FMV (swedish military).

<span style="font-weight: bold">ALL</span> agree that 308 Win and 7.62 NATO can be used interchangeably, with no risk.

I have a copy of the original 7.62 NATO spec (STANAG 2310), it clearly states a <span style="font-weight: bold">CUP</span> mean peak pressure of 50,000 psi, which correlates well with the 62,000 psi piezoelectric of SAAMI/CIP as stated in the above posts.
 
Re: .308 Winchester VS 7.62X51mm NATO

I would suspect that the issues with M14s and commercial ammo with heavy bullets is that they will have slower powders that are incompatible with the M14's gas system, not that it is incapable of firing commercial-pressure cartridges.

Just as I do not load 220 grain bullets with a slow burning powder and blast them through my M1, I would not run 180 grain bullets with an unknown factory powder in an M14.

This is not a pressure issue. It's a timing issue as was discussed earlier in this post. It's not the peak pressure that is relevant, but the area under the curve, which can definitely increase with slower burning powders in any caliber.

This is a consideration for any gas gun, not must the M14 and variants. Anyone who has an understanding of integration and some charts of pressure and time can see that there is a considerable difference between M80 ball and a factory loading with heavy bullets.

I'm willing to bet the numbers are 20% or more difference in force.
 
Re: .308 Winchester VS 7.62X51mm NATO

Yes, and being not adjustable the M14 is particularly prone to these problems. It is not a safety problem but a durability one, many people have bent op rods in relatively short order with hot reloads using heavy bullets + slow powders.

Most commercial accuracy loads with 168 or 175 gr bullets do not have this problem, Ron Smith says they are OK.