7.62 vs .308


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Old 02-21-2011, 01:37 AM   #1
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Default 7.62 vs .308

I've been thinking about a M1A or a FNFAR for hunting and some target shooting, but I'm a little worried about the ammo. I know there is a slight difference between 7.62 and .308 rounds, but I'm not sure how .308 will work in a rifle made for 7.62 and I will be shooting .308 almost exclusively? I have easy access to .308 rounds for hunting, but there aren't a lot of 7.62's around here.
I was wondering what some thoughts are from some of you that have tried .308 rounds in a 7.62 rifle?



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Old 02-21-2011, 02:14 AM   #2
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.308 and 7.62 Nato are interchangable. The round was developed in the U.S. based on the .30-06. Reloading manuals show the Nato equivilents are loaded to slightly higher starting pressures. It's not as readily apparent as it is in the 5.56/.223 variants where the 5.56 Nato can differ significantly enough to cause possible overpressurization inside the breach (for SOME rifles). The FNAR likes them both. The M1A and FNAR are FINE choices. I love my FNAR (heavy barrel). It has no problems feeding either/or. I can't even tell the difference really. I am sure the M1A is the same. I eventually want one of those too. You aren't going to have problems switching between .308 and 7.62 Nato. Unless you have the military surplus flavor, they are mostly identical. Even then, the big differences are in the extra lengths you must go through to de-crimp the brass for primers for reloading.
You're good to go. Make your choice and enjoy!



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Old 02-21-2011, 02:27 AM   #3
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depends on the twist rate of the barrel. most surplus 7.62 is 147grain which doesnt shoot very accurately out of most civilian barrels. its not dangerous to shoot and will function fine just dont expect target like accuracy if your barrel isnt designed to shoot it.

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Old 02-21-2011, 07:25 AM   #4
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Also, you might want to check out the Springfield Armory web site for their M1A owners manual. Its listed under Shooting Tips.

They recommend using 7.62 spec. ammo due to the harder primers. Some .308 commercial rounds use softer primers increasing the possibility of a slam-fire in military style semi/full-auto rifles. I don't really know because I've only shot 7.62 in mine. It could be just be legaleeze or there could be something to it. Just a thought, Ken.

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Old 02-21-2011, 10:28 AM   #5
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The NATO round and the 308 are IDENTICAL. The only difference is that the NATO rounds is loaded to a LOWER pressure than 308 WIN loads.

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Old 02-22-2011, 02:24 AM   #6
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Default Another difference...

The 7.62 NATO chambers are cut bigger to allow for function in less than clean rifles. This usually means only a bit more effort in sizing the brass if one reloads.

Also, in the case of the M14 (M1A) design, be careful of heavy (over 170 grain) bullets. Heavy bullets and slow powders can bend the operating rod of an M1 Garand rifle. I'm not sure about the M14/M1A, but it is based on the same gas operating system.

Any experts with positive information?

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Old 02-23-2011, 03:23 AM   #7
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Quote:
Originally Posted by OldManMontgomery View Post
The 7.62 NATO chambers are cut bigger to allow for function in less than clean rifles. This usually means only a bit more effort in sizing the brass if one reloads.

Also, in the case of the M14 (M1A) design, be careful of heavy (over 170 grain) bullets. Heavy bullets and slow powders can bend the operating rod of an M1 Garand rifle. I'm not sure about the M14/M1A, but it is based on the same gas operating system.

Any experts with positive information?
Spot on. The M14/M1A is slightly more forgiving than the M1 Garand due to the grooved piston, though. But stay below 180gr if using commercial .308Win.

A Schuster gas plug can be used on Garands and M14's to allow for precise gas tuning, too.

And I shoot plenty of 175s in my M14s.
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Old 02-23-2011, 04:01 AM   #8
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Quote:
Originally Posted by cpttango30 View Post
The NATO round and the 308 are IDENTICAL. The only difference is that the NATO rounds is loaded to a LOWER pressure than 308 WIN loads.
I dont have a lot of experience w/ 7.62x51. I always thought NATO ammo brought higher pressures thus making it suspect in non NATO chambers. Similar to 5.56 in that you can fire .223 in a 5.56 weapon but not vise versa. Please let me know if Im wrong.
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Old 02-24-2011, 02:55 AM   #9
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Quote:
Originally Posted by mjkeat View Post
I dont have a lot of experience w/ 7.62x51. I always thought NATO ammo brought higher pressures thus making it suspect in non NATO chambers. Similar to 5.56 in that you can fire .223 in a 5.56 weapon but not vise versa. Please let me know if Im wrong.
The dimensions are the same from .308Win to 7.62x51, but the .308Win is hotter.
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Old 02-24-2011, 05:02 AM   #10
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Quote:
Originally Posted by M14sRock View Post
The dimensions are the same from .308Win to 7.62x51, but the .308Win is hotter.
Thank you for the response. It doesn't make sense to me though.

Looked it up. NATO 50k psi, .308Win 62k psi.


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