In going thru a bunch of old saved documents, I've found that I actually did keep a few copies of posts from long ago & they may be of use to reintroduce in the new gunboards, just to build up our database...this is one of them & I think it was originally from the FAL files[:D]:
.308 Win vs 7.62x51 NATO
About every 3-4 weeks, someone asks the question "Is the .308 Win round different than 7.62x51 NATO?", kicking off a mess of messages explaining this entire issue. What follows is a mini-FAQ, with trailing thoughts from our list members; all of which fairly well covers the issues involved.
If this is deemed sufficient and correct, then perhaps we can just point future question re-askers to this page rather than attempting to readdress this issue.
Let me know if there is more that should be added here.
I've finally dug out my reference materials and, I will try
to make some sense of the 7.62x51mm vice 7.62mm NATO vice .308
Winchester vice 7.62x51mm CETME story.
In December, 1953, the US T65 .30 caliber cartridge was adopted by NATO
as its standard cartridge. What this actually meant was that the five key
members of the alliance agreed to adopt the final version of the T65E3
(soft lead core) as their standard service round. Nominally, the round
adopted by the NATO countries had the following characteristics:
jacketed spitzer bullet of 147 grains (9.45 g) weight, a
brass case (conforming to the US Copper Alloy 260, Annealed,
MIL-C-50 standard) of 187 grains (12 g), for a muzzle velocity of
2750 +/- 50 fps (840 mps) measured 78 feet from the
The round had a variety of names. For example, in the US, the above
round is known as, Cartridge 7.62mm Ball M80 (or M59). In Germany, it is
Patrone 7,62x51mm, DM41A1. In Spain it is the Cartucho Ordinario, 7,62x51mm
Note that of the above nomenclature, there is no mention of a "NATO"
designation for the US or German cartridges. This is because there
were no other 7.62mm rifle cartridges made for and issued to either of the
respective armies. More importantly it is an eloquent statement of the
fact that only the cartridge itself was standardized and adopted. There was
and is no common nomenclature required by the 1954 NATO Standardization
Agreement (STANAG) which codified the adoption of the cartridge.
Spain however, was a different matter. Spain did not join NATO until
1982, and was therefore under no constraints to adopt the common cartridge.
Spain was also the only western European power to successfully adopt an actual
assault rifle (the CETME Model 58) instead of the "battle rifles" (M14,
L1A1, FAL, C1A1, BM59, G3) adopted by the NATO powers. Comcomitant
with the assault rifle, Spain adopted a true intermediate catridge,
the 7.62x51mm CETME. The intent was a cartridge that would allow
ballistic and accuracy performance from the Model 58 akin to that
attained by the 7.9x33mm (7.9 Kurz) fired from the StG44.
The performance and specifications of the 7.62x51mm CETME are
indicative of this intent. Nominal characteristics: jacketed
spitzer bullet of 112.5 grains (7.25 g) weight, a brass or steel case
of 151 grains (9.7 g), for a muzzle velocity of 2493 fps (760 mps).
The construction of the bullet is particularly noteworthy. The CETME
bullet has a 90/10 brass alloy (gilding metal) jacket, with a
plastic nose filler for the first third of the bullet, and a lead
antimony core. That is to say, the bullet jacket is not filled with
the lead core, but has what might be considered a lightweight
ballistic tip (not unlike the kapok tip in the .303 British service round).
This cartridge, adopted in 1957, remained the standard Spanish service round
for the next twenty-five years. Hardly a "diversion" or a flash in the pan!
Confusing the issue, however, were the facts that the external
dimensions of the cartridge were so similar to the NATO round,
and the fact that the
Spanish themselves produced a round to NATO specifications for use, I
understand, in the MG42/58 machine gun. This round was adopted in 1964.
Its specifications were identical to the NATO round mentioned above.
The designation was 7,62x51mm OTAN. Of particular note is the augmentation
to the case necessary to safely fire the NATO load. In 1961, an attempt
was made by the National Factory of Toledo (a Spanish arsenal) to achieve
NATO-esque ballistics by employing a 147 grain bullet at 2,625 fps (800
mps) using the standard CETME case. The attempt failed due to the light
CETME case being too weak to handle the pressures generated by the loading
used. A loading of notably less power than the NATO standard loading.
This cartridge became standard with the Spanish Army after Spain's entry
into NATO in 1982, supplanting the 7.62x51mm CETME. The CETME rifles in
service at that time were modified with new bolt carriers to enable
them to safely use the more powerful NATO load.
Which brings us back to the original issue of .308 Winchester vice
7.62x51mm NATO. As previously stated, the specifications which
have to be met in order for a round to be a NATO standard 7.62mm
are very stringent, and apply to case, bullet, pressure, performance,
etc. The composition and thicknesses of the case are, therefore
rigidly controlled. There are no such specifications for commercial
cases. Something to keep in mind when selecting cartridges for
firearms chambered for the NATO 7.62mm round.
Non-NATO spec cases are the failures experienced by the Spaniards in
1961 when attempting to use lightweight 7.62x51mm cases to emulate NATO
"Cartucheria Espanola (Spanish Ammunition)," Angel Molina Lopez and
Alfonso Orea Maestro, Merino Publishers, Palencia, Spain, 1995
"Die Militarpatronen Kaliber 7,62x51mm NATO ihre Entwicklung und
Abarten (The Military Catridges 7.62x51mm NATO their Development and Variants),"
Brandt, Hamann, Kaltmann, and Kiehn, Journal-Verlag Schwend GMBH,
"US Rifle M14, From John Garand to M21," R. Blake Stevens, Collector
GradePublications, Toronto, Canada
"The FAL Rifle," R. Blake Stevens, Collector Grade Publications,
"Army Ammunition Data Sheets, Small Caliber Ammunition, FSC 1305, TM
43-0001-27,"HQ, Department of the Army
"US Army Manufacturing Engineering Product Guide Book," Section E-2
Date: Fri, 19 Mar 1999 16:38:34 -0800 (PST)
From: Bill Taylor
Subject: Re: .308 Kaboom?
I can understand your frustration over this subject. It has been
rehashed endlessly here and elsewhere.
About all I have to offer is that I have a Steyr Chilean M-1912/61
short rifle, which was converted from 7 x 57 to 7.62 NATO by Chile. If
you are not familiar with the rifle, it is built on a large ring M-98
Mauser action, not the weaker M-95 action of the earlier generation
JUST my own opinion, but I won't shoot "regular" .308 Winchester in
this rifle, only 7.62 NATO. I've been convinced by guys I respect that
there are just too many bad things that can happen by using .308 in it.
OTOH, as a reloader I fully intend to work up loads for this rifle,
probably mostly using cast bullets. It IS 80 something years old,
I'll also be working up loads for my StG-58 and M-1 Garand, both of
which are chambered for 7.62 NATO, as well, altho I'll be using more
normal loads with FMJ bullets with the two gas guns.
Hope this helps a bit.....
- ---Don Brown wrote:
> I have a real headache over this .308 nato vs .308 Winchester thing. I
> would like to know where to find the FACTS rather than opinion about
> shooting these conversions safely. I liked the Chilean M95 .308 - saw
> one at a great price, asked my local gunsmith and was told go ahead
> shoot Winchester. I scoured the web and I get every opinion
> I WANT A .308 surplus, but I want to live. So, do I just have to shoot
> surplus NATO in them? I was just going to go get the Enfield 2-A. I am
> froze like a rabbit in a headlight beam.
Date: Mon, 22 Mar 1999 09:36:41 -0800
From: keith whaley
Subject: Re: .308 Kaboom? -Reply
William Wells wrote:
> That is one for you.
> Good Luck, William
Well, let's put it this way, William.
This is not a debate to see who gets the most points, ya know...
It is meant to offer information, as correct as one can know it, based on
respected and reliable sources.
I too appreciate the new snippet of information Alexander give us, which says
the way SAAMI measured data and the way it is (or was) done in Europe, are
The fact that the "curves" from one to the other cannot give a "constant" you
could apply, is similar to the lack of comparison possible when converting
from CUP to Psi. There too no conversion is possible, as with any given
cartridge the pressure differences are sometimes higher for CUP and sometimes
higher for Psi.
In any case, if one could find a value in both peizo and CUP for that one
cartridge (done by the same lab, preferably) we'd have an instant comparison.
However, unless someone is able to unearth some data gathered by some company
somewhere, we'll never know.
All we know at this point is, the two figures given by Kyrie for the 9mmP and
.38 Super were measured in the same manner. But - we do not have a rational
comparison between 7.62 NATO and .308 Winchester, to get at the whole truth.
I suspect, however, having studied CUP and Psi data for a lot of cartridges,
the values recorded for each method were not all that far apart, regardless of
which was the higher. What I'm saying is, if one showed 24,000 and the other
showed 25,100, you're looking at percentage differences in the range of 7-10%.
You can get those pressure differences shooting on a very hot day!
The point Kyrie has been trying to make involve pressure differences more in
the order of 25% or more!
If Winchester .308's were only some 5-10% higher than 7.62 NATO rounds, one
might be justified in risking that much pressure over
design-operating-pressures. But the possibility is you might run across a
round that develops a pressure well over the weaker gun's PROOF loads!
Probability is very low, indeed, statistically. Possibility is the operating word.
I'd stay away from it even if the possibility was very low.
Let's take an example. Say you know that in one box of ammo out of the 10
cases of ammo you are picking from, one cartridge is KNOWN to be loaded to a
value that is in excess of the proof pressure of the rifle you're shooting it in.
One cartridge only.
Would you take a chance you WOULDN'T draw that box, and that cartridge?
Would you trust your eyesight to that rare possibility? Not me, pal!
Date: Mon, 22 Mar 1999 19:33:05 +0100 (CET)
From: Alexander Eichener
Subject: Re: .308 Kaboom? -Reply
On Mon, 22 Mar 1999, keith whaley wrote:
> I too appreciate the new snippet of information Alexander give us, which says
> the way SAAMI measured data and the way it is (or was) done in Europe, are
> indeed different.
Let me try to put it precisely: US Army data are old copper crusher data.
SAAMI data are most likely piezo-quartz measured and "appear"
significantly higher. Modern CIP data are also piezo quartz measured,
whereas older published CIP data (well into the 1980s), as well as most
ammo manufacturers' catalogues (still) and the legally binding German
"Masstafeln" refer to copper crusher values.
Furthermore, the tapping for the copper crusher port may not be situated
in the same place under SAAMI and CIP specification, ths giving extremely
I came across an article of Manfred Rosenberger as of lately (published in
the 1980s), who bluntly states that the Spanish CETME 7,62 x 51 cartridges
be all experimental and never did enter military service at large. Another
> from CUP to Psi. There too no conversion is possible, as with any given
> cartridge the pressure differences are sometimes higher for CUP and sometimes
> higher for Psi.
> .38 Super were measured in the same manner. But - we do not have a rational
> comparison between 7.62 NATO and .308 Winchester, to get at the whole truth.
> Thank you, I will most likely shoot either NATO 7.62 x 51 or
> reloads in the M98's . The reloads will be aimed at accuracy &
> economy , not max velosity.
> P. S. Are .308 pressures higher than 30-06 ?
Yes sir, they are, though not tremendously so. Truthfully, I think the
problem with .308 Winchester has as much to do with the shape of the pressure
curve as it does its peak. I've seen more problems with Mausers converted to
or rebuit as .308 Winchester rifles than I have with all other cartridges
combined. And that includes some cartridges that have higher allowable peak
pressures than those of the .308 Winchester. While the .308 Winchester is not
particularly interesting in terms of its exterior ballistics, what goes on in
a .308 Winchester chamber is passing strange.
Date: Mon, 22 Mar 1999 18:13:53 EST
Subject: Re: GUNSMITHING: Using older Mauser actions for custom guns ?
In a message dated 3/22/99 4:34:49 PM Eastern Standard Time, firstname.lastname@example.org
> FWIW, Kuhnhausen recommends having M98 type actions re-heat treated
> prior to using them for more modern cartridges.
Respectfully, this is not entirely accurate. He suggests bolts, receivers,
and cocking pieces be checked for hardness, and re-heat treated only if
necessary. That's a blanket suggestion for restoration as well as rebuilding,
and is intended to find and correct problem actions rather than to prepare an
action for any specific use.
>> I too appreciate the new snippet of information Alexander give us, which
>> the way SAAMI measured data and the way it is (or was) done in Europe, are
>> indeed different.
> Let me try to put it precisely: US Army data are old copper crusher data.
Again, what has led you to this conclusion? The US Army TM I've been
quoting gives all the pressures in psi and was last updated in 1991. It gives
no indication that the pressures are crusher of any kind, simply giving all
pressures in psi. There are, among the cartridges listed, two US commercial
cartridges (12 gauge 2.75 inch, and 9 m/m Luger). The pressures listed for
both of these are in psi and are within 500 psi of the corresponding SAMMI psi
pressures. They do not correspond to the SAAMI crusher pressures.
> SAAMI data are most likely piezo-quartz measured and "appear"
> significantly higher.
SAAMI data is available in either copper crusher (CUP) or psi (conformal
transducer), save for those cartridges whose production ceased prior to the
development of the conformal transducer (only CUP is available for these
> Modern CIP data are also piezo quartz measured,
> whereas older published CIP data (well into the 1980s), as well as most
> ammo manufacturers' catalogues (still) and the legally binding German
> "Masstafeln" refer to copper crusher values.
Having just spent considerable time corresponding with one of the
translators of "Cartucheria Espanola" concerning Spanish military pressures
versus CIP pressures, I can say CIP is in much the same position as SAAMI.
True psi, as measured by a sensor in the chamber is preferable, but old CUP
values are still available and used from time to time.
> Furthermore, the tapping for the copper crusher port may not be situated
> in the same place under SAAMI and CIP specification, ths giving extremely
> differently values.
In those case we discussed, piston hole positioning is the same. It may not
be so in cases not discussed. More importantly we did not discuss pressure
barrel specification. It's possible CIP and SAAMI use different pressure
> I came across an article of Manfred Rosenberger as of lately (published in
> the 1980s), who bluntly states that the Spanish CETME 7,62 x 51 cartridges
> be all experimental and never did enter military service at large. Another
> problematic statement.
This is not a field of study where we have a shortage of those :-)
>> from CUP to Psi. There too no conversion is possible, as with any given
>> cartridge the pressure differences are sometimes higher for CUP and
>> sometimes higher for Psi.
> Yes !
Rarely so, but still true. In those cases were it is true, the peak
pressure appears to have been held deliberately low (the 8x57 Mauser being a
case in point).
>> .38 Super were measured in the same manner. But - we do not have a
>> rational comparison between 7.62 NATO and .308 Winchester, to get at
>> the whole truth.
With respect, I think we have a rational comparison - what we lack is a
But to return to the subject of CIP versus SAAMI ... may I make a
suggestion? Let's share sources. I will acquire from SAAMI the complete set of
standards (centerfire rifle, centerfire pistol, rimfire, and shotshell) and
send them all along to you, Alexander. In return you acquire a similar set of
documentation from CIP and send it to me. I think it will be much easier (not
to mention more productive!) if we can each see the reference used by the
We may find the two sets of standards are irreconcilable, and that we
cannot do any comparisons. But we can't know without looking :-)
Date: Mon, 22 Mar 1999 18:13:46 EST
Subject: Re: AMMO/RELOAD: .308 Kaboom?
In a message dated 3/22/99 4:16:46 AM Eastern Standard Time, email@example.com writes:
> The German magazine "DWJ" conducted and published a super-extensive test
> last year with *all* commercially available .30-06 loads. Relative
> pressures were estimatd via an Oehler M 43 strain gage.
And therein lies the problem with strain gauges. As they are not
calibrated, they can produce only relative data :-(