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-   -   .223 vs. 5.56mm SAME as .308 vs. 7.62mm? (http://www.firearmstalk.com/forums/f18/223-vs-5-56mm-same-308-vs-7-62mm-46610/)

CHLChris 08-10-2011 07:44 PM

.223 vs. 5.56mm SAME as .308 vs. 7.62mm?
 
I know all about the higher pressures of 5.56x45mm in the AR-15 platform. A rifle chambered for ".223" should NOT have 5.56mm rounds fired in them because the chamber might go kaBOOM. Whereas "5.56x45mm" chambering means it can handle both rounds.

Is this the same in the .308/7.62x51mm world? I just cannot tell if they are the same or different. I can't tell if one (7.62mm) means I can use both and the other (.308) means I can only use one (like the .223/5.56mm world).

I think my question is clear. Please help!!

HOSSFLY 08-10-2011 07:59 PM

Sorry- wrong post:o

TCH2FLY 08-11-2011 02:27 AM

As I understand it is the opposite for the .308/7.62.
The civilian .308 is loaded to higher pressures than the 7.62, so in the same theory you can use both rounds in the .308 chambered rifle but only 7.62 in a 7.62 chambered rifle.
BUT (note the big but)
from what I have gathered SAAMI says even though they are not the exactly the same they are still interchangeable .... I am not a gunsmith I only play one on TV :D
YMMV

JonM 08-11-2011 02:42 AM

Quote:

Originally Posted by TCH2FLY (Post 560345)
As I understand it is the opposite for the .308/7.62.
The civilian .308 is loaded to higher pressures than the 7.62, so in the same theory you can use both rounds in the .308 chambered rifle but only 7.62 in a 7.62 chambered rifle.
BUT (note the big but)
from what I have gathered SAAMI says even though they are not the exactly the same they are still interchangeable .... I am not a gunsmith I only play one on TV :D
YMMV

this is correct.

Txhillbilly 08-11-2011 02:43 AM

Chris,I'm no authority on this subject.But in all the years that I've been shooting rifles (going on close to 40 yrs),I shot both NATO spec,and Standard spec ammo out of just about every type of rifle chambered for the 2 pairs of ammo.And I haven't ever blown a gun or myself up with either.

The only problems that I really know of,is rifles like the M1A,and Garand need to have ammo in a specific pressure range for the weapon to operate/function with out problems. M14sRock could really go into detail about this for you.

canebrake 08-11-2011 02:47 AM

Chris, don't tell anyone but check here:

.30 Caliber Ammo

CHLChris 08-11-2011 04:05 AM

Cane, I'll keep that our little secret.;)

I was afraid of these answers. Because the answer is, "There is no concrete rule as there seems to be in the .223/5.56x45mm world."

Since I am looking into .308 chambered rifles and there happens to be a lot of reasonably priced commercial loads, I'll probably just choose to stay with .308Win rounds and basically ignore the 7,62 market.

What it seems to boil down to is that the .308 market is pretty firm, but it is the 7,62x51mm market that adheres a little less strongly to common standards.

At least, it also seems murkily clear that a .308Win-chambered rifle would be able to eat most loads in both families.

Generally, on a scoped rifle, I would not be one to have many different brands of loads on hand since each one would perform differently and this rifle is NOT for hunting whitetail. But possibly for protecting my home from the coming welfare-state riots.

robocop10mm 08-11-2011 10:26 AM

And, to complicate matters, some 7.62 X 51 rifles are stamped .308 when that is not the appropriate ammo. HK-91 being the big one. Commercial ammo is ill advised in these fluted chamber rifles as case separations are going to happen eventually. Their roller delayed blowback system is set up for the lower pressures of the NATO round.

cameronguyton 08-11-2011 11:30 AM

I have also heard that the 7.62 NATO has a harder primer than it's commercial counterpart. Using .308 Win in something like a M14 could get a slam fire with a softer primer.

That being said, I also haven't really heard of any problems interchanging the ammo.

I know on my Mini14, it's stamped .223. Ruger's explanation for it is that it can safely fire 5.56 NATO or .223 Remington. If it was stamped .223 Remington, then the 5.56 would not be able to be safely fired.

robocop10mm 08-11-2011 11:49 AM

THe primer issue can be problematic on some designs. The HK has a spring loaded firing pin and slam fires are uncommon.

Ruger cut their chambers to be safe for 5.56, they jsut marked them .223 as 5.56 was not well known when the Mini-14 was introduced.


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