7.62 x 51 or .308, what's the diff?

A

AdVanL

Regular
Rating - 100%
5   0   0
Location
BC Canada
K, so I hate asking things that end up seeming like dumb questions so please excuse my ignorance. I've been looking at a norinco m14 m305, and they're chambered in 7.62 x 51 but people seem to advertise them as .308. I read that .308 has a higher case pressure during ignition (65000 vs 50000 psi IIRC) and it could be dangerous to use them in a rifle chambered in 7.62 x51, yet obviously people do it. I'm just wondering what the gurus here at CGN advise, is 7.62 x51 just a metric .308?
Thanks in advance.
 
maynard said:
Same stuff. Millions of rounds of 7.62 NATO have been fired out of .308 rifles.
Click to expand...

Right, but I'm pretty sure he's asking if its safe to fire .308 out of 7.62. I don't personally own either caliber, but I wouldn't think it's a good idea to shoot the .308 from the 7.62. It's just like you can shoot .223 from a rifle chambered in 5.56 NATO, but it's not a great idea to shoot 5.56 NATO from a .223 because of the higher case pressure.

By all means, correct me if I'm wrong.
 
Most of the supposed difference in pressure between the two is confusion between numbers from copper crusher and transducer measurements. If you have a look at the NATO and CIP pressure maximums in the links below, you will see that they are very close:

http://en.wikipedia.org/wiki/NATO_EPVAT_testing

http://en.wikipedia.org/wiki/.308_Winchester#Cartridge_dimensions

Practically speaking, the main difference is that 7.62 NATO has a greater allowable headspace maximum. This means that you may experience short brass life. A rule of thumb is that if your M14 chamber is more than .010" over the SAAMI "go" dimension, then neck sizing should be used to keep from overworking the brass and extend case life.

As far as 5.56/.223 goes, the main issue is the difference in chamber throat dimensions may cause overpressure if 5.56 ammunition is fired out of a .223.
 
Great, that answers my question perfectly, thanks guys. I'd way rather ask a dumb question and feel dumb for 10 minutes then not ask at all and feel dumb until trial and error blows something something up in my face.
 
Up until a few years ago Radway Green supplied all the ammo for the Imperial meeting at Bisley. In the early years is was 7.62 ball and in the later years it was what Radway Green called 7.62 match. Millions of rounds of 7.62 NATO was fired out of .308 rifles.

In Canada we shot 7.62 IVI out of .308 rifles since the the military stop using .303 and the free .303 ammo went away. Then along came 5.56 NATO. Many Canadian competition shooters had .223 rifles made and shot 5.56 IVI.

Switching between 7.62 and .308 or between 5.56 and .223 was never a problem until the internet came along. Now if there was a real problem and rifles were blowing up because of this, there would be warnings and pictures of blown up rifles all over the internet. Someone please provide me with a link to these pitures.
 
maynard said:
Switching between 7.62 and .308 or between 5.56 and .223 was never a problem until the internet came along.
Click to expand...

SAAMI issued a warning against using 5.56mm ammo in .223 chambered guns 20 years before the internet was invented. Just because you were happy wallowing in your pre-online ignorance, doesn't mean you were right.
 
BattleRife said:
SAAMI issued a warning against using 5.56mm ammo in .223 chambered guns 20 years before the internet was invented. Just because you were happy wallowing in your pre-online ignorance, doesn't mean you were right.
Click to expand...

Let's put it this way. The DCRA and NRA UK use ranges owned by the DND and MOD. If this was dangerous, do you think either the DND or MOD would issue said ammo or allow for one second such unsafe practices to happen on their ranges?

Again please provide links to blown up rifles using 7.62 vs .308 or 5.56 vs .223.
 
I'm with Maynard.
308 and 7.62 x 51 are interchangeable.
223 and 5.56 nato are interchangeable.
I have rifles chambered for all the above.
And ammo stamped with all the above.Which I have reloaded,over and over again. And fired ,over and over again.
So far,Dog has been good to me and nothing has blown up wrong.
 
Advising people to disregard the SAAMI warnings isn't smart in my opinion. The warnings are put out by people who have done scientific testing, not just random scare tactics.

That being said, I'm told that all modern firearms manufacturers of these calibres are designing their rifles to handle the pressures of the higher pressure round (.308 and 5.56) even when they label them as .223.

I'm also told that they are not permitted to export rifles in 5.56 calibre from the US as it is considered a military calibre, so they have to mark them .223 remington or .223 wylde for export. I'm not sure if this is correct though as my Robinson Arms XCR is marked 5.56 NATO and seems to have crossed the border just fine. The registration certificate does say 5.56 NATO as well, so it wasn't that the paperwork was fudged.
 
However.........
M14s, whether US, Chinese, or commercial M1A, have an inertial firing pin. The manufacturers of the civilian versions usually strongly recommend the use of military surplus ammo or military-spec primers to avoid the chance of an AD.
 
You must log in or register to reply here.
Back
Top Bottom