.308 vs 7.62x39 ?

[Garycw]

In looking at getting a hunting rifle in .308 cal. I recently read that a 7.62x39 or 7.62x51 would also chamber and fire. Just wondering if it would be doable, safe or advisable? How do these rounds compare to the .308?

[SC4006]

Firing 7.62x39 in a .308 chambered firearm is definitely not something you should do. 7.62x39 and .308 might have similar sized bullets, but other than that they are completely different and not compatible with each other.

7.62x51 is safe, it is basically the NATO version of the .308 Winchester, the outside dimensions are identical.

[kraigwy]

No the 308 and 7.62X39 are not interchangeable.

The case of the 308 is 51 mm long, the 7.62X39 is 39 MM long.

The 308 bullet is 308, the 7.62X39 is 310-313 (depends on who makes them).

The rim of the 308 is .473 in wide. The 7.62X39 is .447.

When you look at a rifle, on the barrel just in front of the receiver the caliber is stamped.

That caliber and ONLYTHAT CALIBER should be fired in that gun.

Do not go by internet talk, do not go by range commanders, go by what's stamped on that rifle.

Every operator's manual says "only use ammo designed for this rifle". They say that for a reason.

[Garycw]

Originally Posted by kraigwy

No the 308 and 7.62X39 are not interchangeable.

The case of the 308 is 51 mm long, the 7.62X39 is 39 MM long.

The 308 bullet is 308, the 7.62X39 is 310-313 (depends on who makes them).

The rim of the 308 is .473 in wide. The 7.62X39 is .447.

When you look at a rifle, on the barrel just in front of the receiver the caliber is stamped.

That caliber and ONLYTHAT CALIBER should be fired in that gun.

Do not go by internet talk, do not go by range commanders, go by what's stamped on that rifle.

Every operator's manual says "only use ammo designed for this rifle". They say that for a reason.

I've Always used what is stamped on the barrel , without exception. , I just wasn't sure how the 39 would chamber in a bolt action rifle being used as a single shot. Not as a normal occurrence. But as a make do in a emergency.

Very true that you can't believe everything you read. I've seen idiots on YouTube shooting 50cal. BMG out of shotguns. Not that I'd ever try that either.

[tahunua001]

whoever told you that 7.62x39 would chamber and fire from a 308 should not be allowed to be about firearms. 308 is essentially a 7.62x51MM that's been beefed up a little. the two are close enough in dimension that either will chamber in either rifle but due to the excess pressure of 308, it is considered unsafe to fire from a gun chambered in 7.62x51mm. however you can shoot 7.62x51 out of a 308 without issue. however with 7.62x39mm(where the last two digits is the length of the casing) you not only have a slightly larger bullet(311 diameter instead of 308) but you have a casing that is 12MM shorter(51-39). I would not attempt to fire x39 out of a x51 or 308.

[Garycw]

Thanks tahauna, that make sense to me too.
So if a lower powered load was sufficient to be used a 7.62x51 would be ok from a stamped 308 rifle but not 308 out of a rifle stamped 7.62x51. ..and Never a x39 from either.

[tahunua001]

yes, you hit the nail on the head.

[Bart B.]

.308 Win and 7.62x51 NATO are completely interchangeable and have virtually the same peak pressures.

Most folks confuse the different pressure measuring methods each is typically measured with. 50,000 cup NATO round is the same as 60,000 psi .308 round. Military documents often stated pressure in pounds per square inch when copper units of pressure was the system used. Each system gives a different number for the same round. Each system has small differences; a 2000 unit spread across each is normal. The NATO round was originally spec'd at 50,000 cup and the commercial .308 at 52,000 cup due to subtle differences between the systems. Muzzle velocity for a given bullet weight in each is virtually the same.

The USA armed forces bought dozens of thousands (millions?) of .308 Win ammo for use in 7.62 NATO marked rifles.

There's no mention of Winchester beefing up the NATO round to higher pressure nor velocity in the following:

http://riflemansjournal.blogspot.com...f-308.html?m=1

[kraigwy]

The USA armed forces bought dozens of thousands (millions?) of .308 Win ammo for use in 7.62 NATO marked rifles.

Had to be "millions", I my self bought thousands of Fed 308 Match, when I was running the AK NG Marksmanship Program for our M14s.

Fed 308 match is loaded to the same pressures, velocity, specs, as M852 7.62X51 Match.

[tahunua001]

alright we need to develop some sort of consensus. it never fails that if the first poster to a thread brings up the difference in 308 and 7.62x51, the rest of the thread is about why 308 and 7.62 are in fact interchangeable but if the first respondent to a thread says that they are interchangeable then the rest f the thread is about why he/she is wrong and that they are not infact interchangeable so somebody needs to hash this out. this is worse than the .223 VS. 5.56 threads that crop up once a month.

[Bart B.]

Tahuna, the real issue in the cartridge comparisons is the way different places measure peak pressure and the standards they use. Few folks know the details about that. Few folks refer to pointers/links to those details that's oft times put on the internet. Fewer more know how to search for them. And 98% of what's on the internet in print are put there by ignorant (not dumb nor stupid) people regarding the internal and external ballistics of both the commercial and military versions of that great cartridge. We all have our areas of ignorance.

The military specs put in print were also to blame. For decades, the arsenals used copper units of pressure testing small arms ammo. But the unit put in print was "psi" and therein lies a big problem. While people within the actual manufacturing and testing parts of the arsenal knew the difference, all the civilians did not. Along comes electronic strain and pressure sensors measure actual psi numbers the the confusing began.

I, too, was a skeptic until I searched out then read the specs for both military arsenal MIL SPECS and commercial SAAMI stuff.

It's a nightmare. I finally decided decades ago to wake up and get the facts.

[HankC1]

I have Mausers in 7.62x39 and 308. I always worried I may one day pick a 308 rifle and feed and fire a x39. Push feed rifles probably simply would not fire at all, but Mausers are control feed and extractor would hold the case and fire when firing pin strikes!

[Dirty Dan]

I hear conflicting information constantly, from sources that are supposedly unimpeachable...Expert articles, filled with all kinds of officious sounding gobbledgook. One "expert" will deride one another. I think a lot of this back and forth banter, is just that!... .308 Winchester, and its military derivative 7.63 x 51mm, are virtually identical. The loading specs may be somewhat different, but both can be fired from a rifle barrel stamped .308, period..Same thing goes with the .223 and its military clone, the 5.56 x 45mm. Oh, I will receive many curt, condescending comments from you "experts" out there, but to each his own! As for the inter changeability of .308/7.62 x 51mm, and the AK round, the 7.62 x 39mm round. Yes, the 7.62 x 39mm (AK) will chamber, in a .308 Winchester, because it is 12mm shorter than the .308 but that is where the similarity stops! As someone on the thread has brought forth, the case length of a .308 is a full 12mm longer. If the AK round were to be fired, most likely, is a catastropic case failure would result, and that will send super hot gases right back into your face and eyes, God forbid! In the case of .223/ 5.56 x 45, and .308/ 7.62 x 51, no problem. If you must write them down do so, of better yet, mark your ammo boxes accordingly...Like someone before me, on the thread said, when in doubt, go with what the barrel says, caliber-wise, to be safe, and go home from the range with all your body parts. When in doubt, refer to the barrel stamp information. Please be safe on the range, and in this case, ignorance could be lethal, or a life changing, horrible event!

[PetahW]

Originally Posted by HankC1

I have Mausers in 7.62x39 and 308. I always worried I may one day pick a 308 rifle and feed and fire a x39.

Push feed rifles probably simply would not fire at all, but Mausers are control feed and extractor would hold the case and fire when firing pin strikes!

Likely not - when you consider that the rim of the 308 is .473" in diameter & the 7.62X39's rim is larger, @ .447" in diameter.


.

[Dirty Dan]

PETAHW; Got all your measurements correct, but the diminuitive AK round will chamber, in a .308 and I fear could fire, with devastating effect to the shooter, as well as the rifle, necessitating a trip to the optometrist and gunsmith. I don't want to be within a country mile if and when someone does this! I didn't say it would fit, as it's kind of like putting a size 7 foot into a size 8 shoe. Yes, it easily goes in but....Who wants to take the chance??!

[allaroundhunter]

.308 Winchester an 7.62x51mm NATO are completely interchangeable. It really is as simple as that.

[Mobuck]

Whether the Mauser extractor would catch and hold the x39 rim enough to allow firing is a big MAYBE not a confirmed fact. I used a chamber adaptor in a .308 Mauser model 1916. Even with the proper sized chamber, the extractor would slip off about 1/3 of the time. I'd make a SWAG of a 50% chance of firing but most likely the x39 would jump out of the extractor during feeding and end up in front of it when it reached the chamber(or end up crosswise in front of the bolt).

[tahunua001]

I just took a 7.62x39 and fed it into my ruger M77 in 30-06. it fit in the magazine, fed normally and extracted like it should. however I am not about to test my receiver strength by attempting to fire it. the M77 is based on the mauser and uses the same extractor style and 30-06 has the same size case head as 308.

so a word of warning, x39 may fit in a 308 but it won't be a pretty sight when you squeeze the trigger.

[pilothunter]

Thanks!!

QUOTE:

.308 Win and 7.62x51 NATO are completely interchangeable and have virtually the same peak pressures.

Most folks confuse the different pressure measuring methods each is typically measured with. 50,000 cup NATO round is the same as 60,000 psi .308 round. Military documents often stated pressure in pounds per square inch when copper units of pressure was the system used. Each system gives a different number for the same round. Each system has small differences; a 2000 unit spread across each is normal. The NATO round was originally spec'd at 50,000 cup and the commercial .308 at 52,000 cup due to subtle differences between the systems. Muzzle velocity for a given bullet weight in each is virtually the same.

The USA armed forces bought dozens of thousands (millions?) of .308 Win ammo for use in 7.62 NATO marked rifles.

There's no mention of Winchester beefing up the NATO round to higher pressure nor velocity in the following:

http://riflemansjournal.blogspot.com...f-308.html?m=1
"

[SIGSHR]

The idea that a rifle chambered for 308/7.62 Nato can fire a 7.62 x 39 probably originated in Vietnam with all the stories about "They could fire ours but we couldn't fire theirs", and too many forget that while a longer straight walled case can fire shorter case rounds-.357 and 38 Special/Long Colt, 44 Magnum and 44 Special/Russian, the same is not true of rifle cases with shoulders, even if the case in question is shorter and the bullet diameter is the same.

[Sarge]

Bottom of page:

http://www.mcace.com/adapters.htm

Haven't use one myself so I can't comment.

[Garycw]

Originally Posted by Sarge

Bottom of page:

http://www.mcace.com/adapters.htm

Haven't use one myself so I can't comment.

Kinds sounds like a crap shoot. Scares me!

[tahunua001]

The idea that a rifle chambered for 308/7.62 Nato can fire a 7.62 x 39 probably originated in Vietnam with all the stories about "They could fire ours but we couldn't fire theirs", and too many forget that while a longer straight walled case can fire shorter case rounds-.357 and 38 Special/Long Colt, 44 Magnum and 44 Special/Russian, the same is not true of rifle cases with shoulders, even if the case in question is shorter and the bullet diameter is the same.

not entirely accurate. as legend has it, GIs in the south pacific were able to fire 7.7 japanese ammo out of their 30-06s when supplies ran short. of course one should never put too much stock in such tails but just last winter there was a member here that had bought a type 99 arisaka and had issue with his 7.7 brass blowing out and it turns out that his gun had been rechambered to 30-06 by a previous owner and was never marked.

Kinds sounds like a crap shoot. Scares me!

I had a pair of adapters like that. I don't know if they were made by MCcase or not but they came from sportsmans guide. I had one that was 303 brit to 30 tokarev and one that was 7.62x54R to 30 tokarev. extraction sucked but other than that they work pretty good.

[Revoltella]

Since a bottleneck cartridge headspaces on the shoulder, even if the 7.62x39 fit into the 7.62x51 chamber, the firing pin wouldn't be anywhere near the primer.

[Art Eatman]

Revoltella, as mentioned above, sometimes a claw-type extractor can hold a short case against the bolt face.