7.62 X 39 is really a 308


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johned
March 28, 2012, 07:12 PM
Well,

Having beat this to death, and my exhaustion, I finally have a feel for the situation. My original dilemma was "can I put a 308 bore on a 7.62 X 39" gun. Lots of good people have said "NO" because the 7.62 X 39 bullet is "oversize" and would be dangerous. That is certainly good solid advice. Others have said that 309 or 310 should be OK and that is probably true, as well. So who will I kill? Turns out this is a really deep question with some surprising answers. Follow this:

The 7.62 X 39 round is only "sorta" correctly dimensioned. ACTUALLY the round is ....308( .5 or 9) at the leading part/front of the bullet after the Ogive. In the final 5 or 10 thousandths of the bullet the diameter swells to .311. That is like putting a gas check on the rear. With that design it would perform, ballistically, like a full .311 bullet in a .312 or 311 bore. It would also fire safely in a .308 bore. Recently learned that Savage made a 7.62 X 39 that had exactly a 308 bore. No alarms going off in the community about the Savage bolt guns being lethal to the shooter. Also, no "WARNING odd size bore" stamped in the barrel. Others have done this exact same thing with other firearms, including the VZ 58 foundation design and all has worked out swimmingly. The VZ 2008 had a 308 bore and the other Century VZ 58 clones, using us made barrels, had 308 bores. What a cluster FXXX, right? Conundrum...at least...right. The design of the Russian 7.62 X 39 round is the answer as it is 308 "mostly".

Here is the real danger. If I thought that .311 or .312 Russian bullet was actually that size....I might be tempted to HAND LOAD .312 bullets and use them in a 7.62 X 39 chamber. And that might simply explode in my face.

Thank this guy:

Minesweeper3433

Trade Count: (+6)
Senior Member
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Posts: 304

Bullit OVERSIZE
Reply #21 on: Yesterday at 11:22 PM

Quote

Built a 7.62x39 bolt gun on an mini mauser for shooting surplus ammo out of using a 308 bore. Went with 308 as on measuring rounds we pulled found that only the last 5-8 thousandths were larger than 308. Almost like a skirt. That gun shoots great to this day with steel cased ammo or whatever else we feel like putting in it. We put a long 1 degree throat in it as well when ordering the reamer. Although I was always taught that the AK series of rifles had a long throat for that reason. This was however from an instructor at Aberdeen that I didn't hold in to high regard. Will pull a few soviet rounds over seas here today if I can get my hands on a few.
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Old guns like old friendships are long retained and must be constantly renewed. James V. Howe The modern gunsmith Pub. 1934 People where smarter before I was born.

Navy...might have known...right?

Good luck,


John
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armoredman
March 28, 2012, 07:34 PM
I wanted to see, too. So a cartridge, a Wolf HP, gave it's life so that others may learn. First the powder reminded me of H-4895, but surely wasn't anything close. :) The boat tail bullet, (122.5 grains, 1.29 inch long, BTW), measured .308 up to the red sealant band. From the band a stretch of .24 appeared to measure .310, then it tapered to the boat tal. At no point was the bullet .311 or .312.
No pictures, sorry, that hit my camera took wiped out the macro function.

303tom
March 28, 2012, 07:43 PM
Yes 7.62mm is .308 inch ie; .30 caliber............Actually it is little a bigger, like .312. but it is still a .30 cal.

dastardly-D
March 28, 2012, 07:54 PM
Not exactly what you're doing,but I have reloaded regular Sierra 308 into a Russian 7.62x54R and had no problems at all.Aren't they the same diameter bullet ?

solvability
March 28, 2012, 07:57 PM
I have a bunch of pulled bullets from the 7,62x54r can I load the bullets in 308 or 30-06? That would be useful.

I know when I handloaded for 7,62x54r I got the best accuracy from Hornady 312 bullets like I use for my Enfield - hmmm.

Jeff F
March 28, 2012, 08:40 PM
I have loaded .308 bullets in the .303 British with fair to good results then I learned about paper patching and have had very good results. When the Ruger Mini 30 first came out it had a .308 bore, I have never seen any reports of any problems with the surplus 7.62 x39 that has .311 or .312 bullets.

AJumbo
March 28, 2012, 10:17 PM
Marlin made a run of 32-20 lever rifles with .308 bores, and they fired standard 32-20 bullets just fine.

303tom
March 28, 2012, 11:26 PM
I shoot .32 ACP in my .308 with an adapter & they shoot great.........& they are 7.65x17.

Romeo 33 Delta
March 28, 2012, 11:38 PM
I think the 7.62 X 39 is really more .309/.310" as a rule.

I don't see why being .002" overbore in a strong action with reasonable loads and a 123gr bullet would be a problem ... HOWEVER

When I feel the need, I take some of my .309/.310" bullets and run them through a .308" Lee sizer die ... very little effort is required to do this, so that's telling me that the jacket is not overly thick (like when I take my Hornady Carcano .2675" bullets down to .2660" ... that takes a bit of effort because of the thicker jacket) and I'm not changing the diameter by all that much.

Now I've been told that this causes problems with the jacket/lead core set up, but I've not seen any accuracy problems ... but then I'm shooting at 50 and 100 yards so maybe it just doesn't show up at that distance.
Just my 2 cents worth ... your results may be different.

I believe that Ruger used a .308" barrel on the Mini-14 ... but with a longer throat to help ease the larger bullet through. I don't know about the Model 77. I have both but never checked the 77's groove diameter. I'd be surprised if they would have opted to have two different barrels for the same caliber???

Fishslayer
March 29, 2012, 01:16 AM
When the Ruger Mini 30 first came out it had a .308 bore, I have never seen any reports of any problems with the surplus 7.62 x39 that has .311 or .312 bullets.

I have one of those early Minis. I've put a hunnert or so of the Yugo milsurp x39 through it. Works just fine.

R.W.Dale
March 29, 2012, 01:34 AM
I shot hundreds of rounds of monarch through my 7.62x39 savage bench gun I built. Even after I reamed it to an "improved" version of 7.62x39

posted via mobile device.

mac66
March 29, 2012, 09:08 AM
My original Mini 30 has a .308 bore and I shoot military x39 ammo in it with no problems.

Driftertank
March 29, 2012, 09:32 PM
Seems to me, if it really concerns someone, it shouldn't be to hard to have a barrel gauged. As has been previously stated, i don't think .002-3" would cause a problem, as when loading a .310-.311 diameter bullet for a .308 bore, unless you're running close to pressure peak. I WOULD, however make sure to have the bore gauged before trying to load .312 (nominal) bullets, as they'd probably cause issues in a .308 bore.

I wouldn't recommend loading 54r bullets in .308 without mic'ing them.

I would think many US ammunition manufacturers would likely lean towards .308 bullets, or at least tapering as notid by the OP, since loading overbore rounds could cause safety issues, while loading underbore only hurts accuracy.

DoubleTapDrew
March 29, 2012, 10:06 PM
I read at some point in time on some forum (probably here) the difference is where it's measured. Americans measure the bore size from the diamater between the lands and the ruskies measure the diamater from the grooves. So the bullet diamater is the same in spite of the claimed bore diamater.
Not sure if that's true or not but would explain the .308 vs .310-.312 stuff.

ApacheCoTodd
March 29, 2012, 10:21 PM
Damn, a 7.62 X 39 is a 7.62? Sure, and Pluto is a planet!:D

303tom
March 29, 2012, 11:24 PM
I read at some point in time on some forum (probably here) the difference is where it's measured. Americans measure the bore size from the diamater between the lands and the ruskies measure the diamater from the grooves. So the bullet diamater is the same in spite of the claimed bore diamater.
Not sure if that's true or not but would explain the .308 vs .310-.312 stuff.
I was weighting on someone to speak up that knows what they are talking about, way to go Drew...........

R.W.Dale
March 29, 2012, 11:44 PM
I was weighting on someone to speak up that knows what they are talking about, way to go Drew...........

The nomenclature about bore and groove diameter means essentially nothing beyond the nonsensical way cartridges are named.

Think of this
7.62x39
7.7x58 jap
7.65x53 Mauser
.303 British
7.62x54r

All the above use the same bullet diameters plus or minus a couple thousandths

Then you have
7.62x51mm
7.5x55
7.5x54
300 sav to mag
30-30 to 30/06

These all use the same bullet diameter nominally

But the really important tidbit to understand is 7.62x39 runs on the very smallest side of the topmost list and can indeed be quite happy shooting bullets from or being shot in barrels for the bottom list.

Russian 7.62 tends to have a slightly larger groove diameter than what we call 7.62 in the west .310 vs .308"

But the Russians also use a deeper rifling and most of the time will have the same .300" bore that we call 30 caliber here.

posted via mobile device.

303tom
March 30, 2012, 09:27 AM
The nomenclature about bore and groove diameter means essentially nothing beyond the nonsensical way cartridges are named.

Think of this
7.62x39
7.7x58 jap
7.65x53 Mauser
.303 British
7.62x54r

All the above use the same bullet diameters plus or minus a couple thousandths

Then you have
7.62x51mm
7.5x55
7.5x54
300 sav to mag
30-30 to 30/06

These all use the same bullet diameter nominally

But the really important tidbit to understand is 7.62x39 runs on the very smallest side of the topmost list and can indeed be quite happy shooting bullets from or being shot in barrels for the bottom list.

Russian 7.62 tends to have a slightly larger groove diameter than what we call 7.62 in the west .310 vs .308"

But the Russians also use a deeper rifling and most of the time will have the same .300" bore that we call 30 caliber here.

posted via mobile device.


Damn Dale, your right again.............

DoubleTapDrew
March 31, 2012, 12:31 AM
These all use the same bullet diameter nominally

But the really important tidbit to understand is 7.62x39 runs on the very smallest side of the topmost list and can indeed be quite happy shooting bullets from or being shot in barrels for the bottom list.

Russian 7.62 tends to have a slightly larger groove diameter than what we call 7.62 in the west .310 vs .308"

But the Russians also use a deeper rifling and most of the time will have the same .300" bore that we call 30 caliber here.

Sooo...
I should stop shooting 7.62x39 out of my M1A? lol jk :p

Driftertank
March 31, 2012, 01:03 AM
On a related note, a friend texted me the other day asking if there was another name for 7.62x39, because he was trying to buy some ammo for his Tantal, and the chick at the gun shop he went to said .308 was the same thing.

I told him no, and regardless of whether she was stupid (or rather ignorant), he shoul buy his ammo, and anything else firearms-related, somewhere else...

303tom
March 31, 2012, 07:10 AM
On a related note, a friend texted me the other day asking if there was another name for 7.62x39, because he was trying to buy some ammo for his Tantal, and the chick at the gun shop he went to said .308 was the same thing.

I told him no, and regardless of whether she was stupid (or rather ignorant), he shoul buy his ammo, and anything else firearms-related, somewhere else...
Yes, .30 Caliber Russian..................Not .308 Winchester.

Driftertank
March 31, 2012, 09:56 AM
Ah, but 54r is also ".30 caliber Russian," and it won't work in his gun either. Also, since i've never seen a box of ammunition labeled ".30 caliber Russian" i wouldn't consider it a legit term for 39. Especially when dealing with someone who thinks .308 Win is the same thing...

Cemo
March 31, 2012, 11:06 AM
My RCBS reloading die set came with two sizes of neck sizers, one is .308 and the other is a little larger at .311.

dexter
March 31, 2012, 07:49 PM
Hornady 7.62 123gr sp is marked .310 on the box.It also mics .310.

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