I have read a lot about 308 Win, and the 7.62 NATO. I own a M1A in of course, 7.62 NATO and have just acquired the Remington M700 VTR Desert Recon rifle in 308 WIN. Will it hurt to shoot NATO ammo in this rifle as there is the slightest pressure to close the bolt! I always heard the military rifles in 7.62 NATO as the 5.56 mm rifles are the same except those military rifles have longer throats! Any schools of thought on this subject would be helpful! Happy July 4th, SEMPER FI!

I don't think it will hurt to shoot US made ammo, as it is to SAMMI specs.

With foreign ammo, I'm not so sure, although I've shot it before. Dimensions of the chamber of some rifles are more generous than others, and foreign ammo MAY correspond to this. I think .308 is a higher-pressure round than NATO, and I shot it in my M1 A (which I no longer have) with no problem. It was Winchester white box ammo, IIRC.

Real high pressure can bend the Operating rod on a M 1A. And a lot of surplus NATO ammo (like South African, Australian, etc.) is fine ammo, but these countries not being NATO, a test would not be out of order.

I seems the difference is not so much the throat as the headspace and the pressure, here is a link to a very good article by our own Steve Redgwell:

http://www.303british.com/id36.html

I fired a few 7.62's in my Savage .308 without problem, but they were all US made - weren't nearly as accurate as commercial (even the match stuff) so I quit pretty quickly. YMMV

Thanks guys, just don't have any 308 WIN brass, but 1000's of NATO 7.62. Just wont reload them, they do shoot exceptionally good thought!

I believe Nato ammo has its own set of standards and follows CIP more the SAAMI. Not that it makes a lot of difference in the pressures of most cartridges that are both NATO and SAAMI registered (308-7.62 or 223- 5.56 as example)
http://en.wikipedia.org/wiki/NATO_EPVAT_testing

Why not??

Ream or swage the crimp, back off your load a couple grains and load them puppies up. Mil brass and 147 grain Machinegun pulls from Hi-Tech is half the reason I own so many 308's.

I'm betting a former Marksmanship Instructor can do things with military brass and pulled MG bullets that 90% of the keyboard jockeys on here would say is impossible

Hell, if you ain't goin' to shoot them, I'll send you some green and you can ship them to Montana...

+1 to what Dan said. I think any potential issues are with the loaded rounds, none with the fired brass - other than the extra work getting it ready the first time. In addition to the primer pockets needing to be swaged, you may find that the initial resize requires quite a bit of effort - I bought a Rock Chucker for exactly this reason, to resize brass fired in an M1A.

GL with the new 700 btw.

The only possible issue with NATO brass is a diminshed case capacity which would raise pressures. Military brass is a bit thicker (not always, but sometimes.) I'd back off 5% just for an abundance of caution.

I need to clear up something maybe! I'm shooting factory loaded NATO rounds which do have the plus sign in the circle! Some from Spain and some from merry ole England, I have not reloaded them, I just read an article a few weeks back about what the difference was and thought that had cleared up my cunondrum! I think I still need to read more! The only thing I read are Rifle and Handloader so will have to go and find the article before I make a donkey out of myself! Me and Little Brother are shooting the crap out of this new rifle though! Otis!

I bought the M700 VTR for a job offer I have to go work off the coast of Samolia, something about those pesky little pirates!

I tried some military ammo in my Mod 7 years ago,the bolt got stuck good using it,so I just threw it in my ammo locker and haven't used it since.
I was told it has a higher pressure because it is made to function in a MG.

There are differences in the chamber specs between SAAMI 308 Win and 7.62 NATO. For example the SAAMI 308 minimum headspace is 1.630" and the NATO is 1.645" The Reject Headspace dimensions are 1.638" SAAMI and 1.6455" NATO.

Here's where it get's a bit interesting. All ammo (Commercial and GI) I've measured has gauged at less than 1.630". This means that odds are that NATO ammo "should" chamber in either chamber. The concern arises when you use a commercial round in a NATO chamber toward the long end. This would be a combination of short ammo and long chamber headspace and weaker brass. Will the commercial case hold in this excessive headspace condition? The GI cases are heavier and seemingly stronger and have an extra margin of safety built in.

My M1A came with a SAAMI chamber, and I kept using a SAAMI through rebarrels. I fired fair amounts of arsenal loaded LC M118 and M852 ammo through my barrels without problem. During my time competing with the M14/M1A, I monitored chamber headspace, and when I fired reloads, monitored cartridge headspace meticulously. I was guarding against a overlong round causing a slam-fire. I used the tougher LC brass for other reasons. Namely, the M14 is notorious for stretching brass during the firing cycle. The stretch/resize cycle caused separations after 5 or so reloads. The convention was/still should be, no more than 4 or 5 reloads on a case. Possibly less with the thinner commercial case.

The heaver military cases do not "cause" higher pressures in the arsenal loaded rounds. Arsenals load to a pressure specification. SAAMI and NATO are only slightly different. The higher pressures come when folk reload GI cases using data they worked up for commercial cases. The convention is drop your load 10% when you switch to GI cases then work up again.

FWIW, the USMC chambered their Match M14's with a SAAMI Chamber and kept them at or near minimum (1.630"). They shot lots of Lake City M852 through those guns.

NATO doesn't have a separate machine gun specific round. Some Indian 7.62 (which isn't NATO, of course) was de-belted and (I hear) the process pushed back the bullets. It's widely reported, anyway.

NATO ammo is reportedly loaded to less pressure than .308.

Otis,
I re-read your original post. I don't think you're headed for trouble. The hard bolt closing with the 7.62 rounds in a 308 chamber could be from the bullet engaging the throat earlier causing a bit of resistance.

If you're not inclined to reload your 7.62 brass, PM me and I'm sure we can work out a deal to get you more money to buy ammo or toys with.
Chris.

If it's English or Spanish brass, I doubt it's reloadable.

It is not reloadable! It only took me two decapping pins to figure it out! I shoot this stuff in my M1A all the time, I even pull the FMJ and reload Nosler Part. in them when I want to have quick follow up shots for hogs in the swamps! Will only be allowed to use FMJ or "ball" in the ocean! Don't want to burn up good ammo on pests!

Military surplus brass is capable of really good groups. These pix were formed by 155 grain bullets with minimal brass prep. The primer pockets were swaged and I trimmed the flash holes. Finally, they were all trimmed to 2.000" I should point out that none of the cases were sorted by weight or had their necks trimmed.

Milsurp brass is capable of fine performance. Reloaders should not get too carried away with the hype surrounding expensive, European made cases. High end, expensive brass has its place to be sure, but for hunters or military rifle shooters, shoot the milsurp stuff and save.



The first picture shows a five shot group at 100 yd using 155 Sierra MKs. It measured 0.459 inches. The overall group size for ten different powders at 100 yd was 1.007 inches



This second picture shows the best group using 155 grain Hornady VMAXes. It meaasured 0.481 inches. Slightly larger than the Sierras.

Overall, from my rifle, the Hornady AMAXes produced an average groups size of 0.715 for ten powders. Granted, this was only at 100 yards, but it formed the basis for further testing.

The Hornady bullets grouped tighter as fired from my Tikka HB, with all ten powders grouping less than an inch. With the Sierras, only five of the ten powder loads did better than one inch.

I think we each need to determine the degree of difficulty we will accept when reloading. I've reloaded military 308 since 1979, when I bought a 308. I dropped the powder 10% and worked up from there, I never had any problems other than the need to swage or chamfer the primer pocket. The Lee decapper has worked great for me and I'm on my first one of them. I don't remember when I bought it but it was just after they sold them a separate item. I use the RCBS primer pocket swage tool on the brass. My 223 was several years old before it had any civilian brass through it. I've had only good experiences with boxer primed military brass and hope I have many years left to use it. I do run them through the case trimmer after I size them because much of my brass was fired in a machine gun. DRMO can be your friend. :-) YMMV

I have reloaded Lake City most of my life! Never had any trouble with the brass! I use what I get, and most is from friends who don't reload. They know I would love to have it! Like any brass I come up with, I save it, sooner or later me or someone in my family will end up with a paticular calibre' and we will need to load some rounds! All my 223 REM is military surplus! I think it was Speer, but don't qoute me, that said all the data developed for the tables used military brass so you didn't need to reduce and work up! As always read before you reload! I might not shoot as good as I used to, but I can still hit what I'm trying to! Shot the M700 VTR in Desert Recon, at Fort Lewis last Saturday, one group was three shots under a half inch. Then just started shooting rocks at 350 yds! Hope to do some more shooting in El Paso now that changed job sites!

from Yahoo answers:

308 Win vs. 7.62x51--The Straight Scoop
Before we go much further, I want to address the oft-posed question "Are the .308 Winchester and 7.62x51 NATO one and the same?" The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635" for the 7.62x51. The .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "[N]obody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62x51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max. Reloaders should also note that military ammo often is made with a thicker web. Consequently the case capacity of 7.62x51 brass is usually less than that of commercial .308 brass. You may need to reduce recommended .308 Winchester loads by as much as 2 full grains, if you reload with military 7.62x51 brass, such as Lake City or IMI.
Source(s):
http://www.6mmbr.com/308Win.html

The 6mmBR.com reference and Dean Speir's site - http://www.thegunzone.com/30cal.html - make this discussion about the differences between 7.62x51 and the 308, the second most read page at my site.

I see my articles about the 7.62x51mm mentioned around the Internets. It's nice to see. The original article is here - http://www.303british.com/id36.html

Too bad I don't get residuals like they do on TV.

I'm sorry, but this is WRONG.

Max pressure for 7.62x51 nato is 50,000 CUP.... CUP, not psi
There is no conversion from CUP to psi.

Recent measurements indicate max pressure to be 61k. So,

308 - Max pressure 62k PSI
7.62 NATO - Max pressure 61k PSI


This 50k max psi for 7.62 nato is really widespread on the web, im not sure why... >.<

SAAMI CUP, CIP CUP, SAAMI PSI and CIP PSI are four different measurement systems. So if you know the CIP CUP, you can't directly substitute it for SAAMI CUP, but you can calculate the conversion.

None of the four systems are perfectly precise. If you give a technician 10 rounds out of a near-identical lot and have them tested, then give the same tech using the same equipment on the same day with the same phase of the moon another 10 rounds out of the same lot, you'll generally do well to get within plus or minus 1,000 PSI of the original test. The different measurements can be converted to each other with about that same precision.

IIRC, the NATO pressure measurement system is it's own system, closer to CIP than to SAAMI.

SAAMI originally held that what we call CUP today was actually the same as PSI. Measurements taken on the old copper crusher system were commonly reported as PSI. When better equipment became available, it became apparent that the copper crusher system was underestimating pressure on the high end. So SAAMI reversed itself, saying that PSI and CUP were no longer equal, and in fact were not even correlated, a mathematical impossibility. So SAAMI was 0 correct out of 2.

WELL, NO RESIDUALS HERE EITHER, !

Just a BIG thank you for your article !

Not going to get technical here.Both .308 & 7.62x51 can be fired in a 7.62x51 chamber.If you fire 7.63x51 in a .308 chamber you will void your warranty.They can tell.Something about slamming the shoulder into the bottom of the chamber.