Sorry for the delay, but most folks were closed till after the first of the year.
I sent e-mails or talked to every U.S. ammo manufacturer whose address I could get. Some didn't respond (yet?)
Here's what they answered (my e-mails were basically the same, so I'll only post it once):
Dear Sir,
A safety question has come up on the forums of our organization.
Specifically is your .308 ammunition safe for use in rifles chambered for 7.62 NATO?
Thank you for you response.
Leon Rogers
Chairman, Board of Directors
Predator Masters Inc
It should, but that would depend on the rifle. I¹ve never seen it not workin the NATO chamber, but some day, someone, will likely find one that our308 ammo won¹t work in it. Tim (Buffalo Bore)
Thank you for the email. To clarify, our 308 loads are manufactured at a Lower pressure so they are able to be used in a 762 chamber.
Thank you and Happy New Year! (Ultramax)
Will work fine guaranteed, thanks (Georgia Arms)
All of my ammunition is manufactured to my clients specifications within SAAMI regulations. ..308 Winchester is identical to 7.62 x 51mm NATO Obviously different bullet weights/types need to be utilized for barrels of different twist rates, and/or action types to ensure proper accuracy and function. Good Shooting, John (Safari)
Yes, it is 100% safe. Feed, function, and accuracy all are very good in 7.62 rifles as well. Mike McNett (DoubleTap Ammunition)
Yes, our ammo is safe, but depending on the semi-auto platform you are using you may experience premature extraction which appears to be high pressure. (Nosler)
Mr Rogers, Our 308 ammo will fire safely in bolt action rifles chambered for 7.62X51. The cartridges are dimensionally the same. The problem comes when firing our hunting ammo, which is loaded with slower burning hunting powders, in AR type rifles.
Doing so causes auto action rifles such as the M1A or AR-10 to develop higher gas port pressures causing these rifles to run hard because the pressure remains for a longer period of time. AR loads use medium rate powders that create lower operating pressure. Therefore, actual 7.62X51 loads work better in ARs than 308 hunting loads. Our Performance Match ammo works well in both AR and bolt gun platforms. The FN/FAL rifles have an adjustable gas system to compensate for this issue. The AR-10 can be fitted with one. Hornadys reloading manual #5 lists data for the 7.62X51 separately from the 308 loads. Linn. COR-BON. Technical support. (Corbon)
Added 1/7:
Sir, Yes, commercial .308 is safe to use in mil-spec chambers. Thanks, (Federal Ammunition)
Still waiting on replies from Winchester and Remington, but it sounds as though the ammo manufacturers maintain that their .308 ammo is safe to fire in 7.62 NATO chambers.
BUT!!
Hang on folks, that's not the end of the story.
In SAAMI's
"TECHNICAL DATA SHEET, UNSAFE FIREARM-AMMUNITION COMBINATIONS" they DO NOT have any warning at all about the 7.62 NATO/.308 Winchester.
Just to make absolutely, 100%, bet the food money sure, I also called Rick Patterson, the Managing director of SAAMI. Though he did say it was SAAMI's default fallback position, He outlined the SAAMI OFFICIAL POSITION:
Dear Leon:
It was a pleasure speaking with you yesterday—thanks for contacting SAAMI with your 308 Winchester vs. 7.62x51 NATO question.
SAAMI has a simple safety rule. It is one of the “Ten Commandments” of firearm safety. ALWAYS make sure the caliber stamped on the head of the cartridge matches the caliber stamped on the barrel of the firearm. Only then can you ensure the safety of the firearm/ammunition combination. If in doubt, contact the manufacturer of the firearm or take the firearm to a gunsmith who can make a cast of the chamber.
Please let me know if there is anything else I can do to help.
All the best,
Rick
Richard Patterson
Managing Director
Sporting Arms and Ammunition Manufacturers' Institute, Inc.
So there you have all the info I could gather, make your own decision.
.
.
.
.
.
.
.
.
.
Oh yeah, there is one more thing. This was the rest of Rick's e-mail:
BTW, I also had a chance to go through your web site and am happy to say I’m officially registered (display name “techspecs”). I’m currently waiting for delivery of a Bushmaster Predator specifically to use on coyotes here in Connecticut. Can’t wait!
Rick is a fellow predator hunter and now a member of Predator Masters.