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Joined: Apr 2001
Posts: 9,717
Campfire Outfitter
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Campfire Outfitter
Joined: Apr 2001
Posts: 9,717 |
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. 
Safe Shooting! Steve Redgwell www.303british.comGet your facts first, then you can distort them as you please. - Mark Twain Member - Professional Outdoor Media Association of Canada ![[Linked Image from i.imgur.com]](https://i.imgur.com/AP39Jhm.jpg)
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Joined: Aug 2010
Posts: 1
New Member
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New Member
Joined: Aug 2010
Posts: 1 |
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 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... >.<
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Joined: Jun 2004
Posts: 11,115
Campfire Outfitter
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Campfire Outfitter
Joined: Jun 2004
Posts: 11,115 |
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.
Last edited by denton; 08/14/10.
Be not weary in well doing.
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Joined: May 2005
Posts: 1,880
Campfire Regular
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Campfire Regular
Joined: May 2005
Posts: 1,880 |
WELL, NO RESIDUALS HERE EITHER,  ! Just a BIG thank you for your article !
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Joined: Jan 2007
Posts: 7,297
Campfire Tracker
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Campfire Tracker
Joined: Jan 2007
Posts: 7,297 |
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.
Ideas are far more powerful than guns, We dont let our people have guns. Why should we let them have ideas. "Joseph Stalin"
He who has braved youths dizzy heat dreads not the frost of age.
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