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- - 7.62x51 mm out of a bolt action?? (http://goldismoney.info/forums/showthread.php?t=348873)

Victor | 02-12-2009 10:37 PM
7.62x51 mm out of a bolt action?? Anyone have any first hand experience shooting 7.62x51 mm out of a .308 Win. bolt action? Any issues with safety or accuracy? I am assuming the military does it but was not sure if it was possible or recommended. I want to be able to use 7.62x51 mm in both an M1A and a possible future .308 bolt action. Right now I shoot 7.62x51 mm in the M1A. I do not want to stock different ammo for the semi auto and a bolt gun. I also will not shoot .308 out of the M1A. I want to be able to use 7.62 in both weapons. Thanks all....

igorthesmall | 02-12-2009 11:25 PM
Re: 7.62x51 mm out of a bolt action?? You can shoot nato out of .308, but generally not the opposite.

CyberGold | 02-12-2009 11:44 PM
Re: 7.62x51 mm out of a bolt action?? I've shot an abundence of NATO surplus out of a couple of Rem 700's

SilverCity | 02-13-2009 12:12 AM
Re: 7.62x51 mm out of a bolt action?? Won't be any problems...other than accuracy. My Rem 40X (7.62 Nato) shoots M118 Match 172 grain into .5 MOA and the 147 grain ball into about 1.25-1.5 MOA. Same with the Rem 700 VSSF (308). U.S. GI 7.62x51 Nato M-80 designated bullets have a slightly eccentric axis to enable machine guns to shoot in a CONE of fire rather than tight groups. Not sure if all nato countries followed this specification.

TTAZZMAN | 02-13-2009 12:23 AM
Re: 7.62x51 mm out of a bolt action?? 308 vs 7.62 one of the most contreversial subjects in shooting as for MY OPINION i have both a DPMS ap4 chambered in 7.62 and a DPMS LR308l chambered in 308w and a Remington VTR bolt 308w i reload 308w so i only reload cases shot in the correct camber i really have no issue shooting either in either but not if your reloading If you want ultimate accuracy i would shoot what the chamber is, i would never reload 308 shot in a 7.62 chamber, you will find very opinionated arguements both ways on this subject i subjest you google the subject and read all the opinions and why and make up your own mind I never have shot 7.62 thru the Bolt 308 because the word is 7.62 develops more pressure and doesnt have the semi-auto action to release some of that force but i have shot 7.62 thru the Semi-Auto 308 without any issues again these are myown personal opinions only

SilverCity | 02-13-2009 12:31 AM
Re: 7.62x51 mm out of a bolt action?? From Wikipedia: The 7.62x51mm NATO is a rifle cartridge developed in the 1940's and 50's as a standard for small arms among NATO countries. Specifications for the 7.62x51mm NATO cartridge are not identical to the commercial .308 Winchester though they are safely interchangeable. (according to SAAMI specifications)

Eulenspiegel | 02-13-2009 01:04 AM
Re: 7.62x51 mm out of a bolt action?? Wikipedia is wrong. They are not safely interchangeable. .308 has higher pressures than 7.62 NATO. So, you can fire 7.62 NATO rounds in a .308 gun, but I would not do the reverse.

SilverCity | 02-13-2009 01:21 AM
Re: 7.62x51 mm out of a bolt action?? The problem is actually related to HEADSPACE. The 7.62 Nato chambers are cut LONGER than commercial chambers to allow for excess fouling under battlefield conditions. Generous 7.62 Nato headspacing coupled with higher commercial 308 loadings and thinner commercial 308 brass may cause another problem (excess pressure) if the chamber is out of spec. This can easily be verified by a competent gunsmith. Wikipedia merely referenced the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) which issues no official safety warning about interchanging these two cartridges. If the condition of any military surplus weapon is in question, it should be thoroughly checked before firing. Ammunition should be of KNOWN origin and quality before using it. The original question was whether 7.62x51 could be safely fired from a .308 chambered bolt action rifle. With the above qualifications, the answer is yes.

horseshoe3 | 02-13-2009 02:44 PM
Re: 7.62x51 mm out of a bolt action?? SilverCity is correct on the headspace issue. .308 headspace is held to much tighter tolerances than 7.62. There will be no danger firing a 7.62 round in a .308 rifle. However, if the .308 chamber is on the short end of tolerance, and the 7.62 round is at the long end, you may have trouble closing the bolt. If you can close the bolt, it is safe to fire. There MAY be a danger when firing .308 ammo in a 7.62 chamber. If the 7.62 chamber is at the long end of tolerance, it will be out of spec for .308. This is on a per rifle basis. If the headspace is excessive, it may result in case head seperation. Have a gunsmith check your 7.62 chamber to see if it is also OK for .308. Chances are that it will be and then you can confidently shoot either. One other caveat for the M1/M14 system is that you do not want to use too heavy of bullet (over 180) or too slow of powder as this will cause problems. The chamber pressure will be fine, but the pressure will not have dropped off enough by the time the bullet passes the gas port. This will exert too much force on the op rod and possibly bend it over time.

horseshoe3 | 02-13-2009 02:45 PM
Re: 7.62x51 mm out of a bolt action?? Quote:
U.S. GI 7.62x51 Nato M-80 designated bullets have a slightly eccentric axis to enable machine guns to shoot in a CONE of fire rather than tight groups.
Can you provide a source for this? I've never heard of it before.

SilverCity | 02-13-2009 02:52 PM
Re: 7.62x51 mm out of a bolt action?? Quote:
Originally Posted by horseshoe3 (Post 1568430) Can you provide a source for this? I've never heard of it before.
I don't have anything current. My source was military spec sheets that I read some years ago. I will see if I can locate it... Here is something from "Cartridges of the World", 8th Edition, Ch. 17, p.449-450: Cartridge, 7.62, NATO, Test, High Pressure, M60 (used to proof-test barrels and weapons) Pressure: 67,500 +/- 2500 PSI, Avg Cartridge, 7.62, NATO, Ball, M80 Weapon: Gun, Machine, 7.62mm, M60; M73 Rifle, 7.62mm, M14 Pressure: 50,000 PSI, Max, Avg. Accuracy: 5" mean radius, max. avg. at 600 yards; Extreme Spread, max. per target--25 inches In other words, U.S. GI M80 ball was spec'd to shoot 10-25 inch diameter groups at 600 yards. What I would call a CONE OF FIRE. By contrast, match-grade M14s are capable of 3 inch diameter groups at 600 yards (with match ammo). Not sure where to find more detailed bullet specifications....sorry.

horseshoe3 | 02-13-2009 05:28 PM
Re: 7.62x51 mm out of a bolt action?? Those are the acceptance standards. It was not accepted if it shot any worse than that. Of course, tighter groups were always accepted.

TTAZZMAN | 02-13-2009 05:39 PM
Re: 7.62x51 mm out of a bolt action?? "5" mean radius with a 25max spread" doesnt mean 10-25" to me but im not argueing, i do know my standard nato head stamp 7.62 ammo doesnt exibit that level of deviation, the idea you state does make perfect sense to me for machinegun ammo though. this 308 vs 7.62 thing is as old as the cartriges and great arguements both ways for what its worth a 308w and a 7.62 outer case spec dimmensions are exactly the same 7.62 chamber is spec'd longer 308w and 7.62 develop different pressures, the 7.62 is higher, but the measuring specs are different, most say the 7.62 is a higher pressure round 7.62 brass is thicker so the volume inside the brass is smaller DPMS says you can shoot both rounds in the 7.62 chamber in their guns but it voids the warrenty if you shoot 7.62 in a 308chamber along with other non sammi ammo brands Just some thoughts

SilverCity | 02-13-2009 07:07 PM
Re: 7.62x51 mm out of a bolt action?? Pinpoint accuracy isn't needed in an automatic weapon. Increasing "hit probability" is....hence "cone of fire" either by accident or design. There is even a DUPLEX ball load for the M14 which uses two bullets, designated the M198. A FRONT bullet, 84 grains, 2750 fps, 2 inch mean radius @100 yds (4 MOA in my book) and a REAR bullet, 85 grains, 2200 fps, between 5-10 inches CEP at 100 yards...all designed just to increase M14 "hit probability" at a given distance.

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