7.62x39 improved?

[nekshot]

I was sitting in my treestand with my crossbow and again got to thinking about those neat little mausers in 7.62x39 and got to wondering has any one ever improved this cartridge and if not why not? Surely with a little more room in the case and in a strong action a 110 gr should get close to 3000fps. Maybe I am too optomistic but you surely should get that 150 gr bullet fairly close to 2500 fps. I don't even think .308 bore for this cartridge, I prefer the .310-311 bore. In a improved version no unsuspecting publican would stick one in a ak! If a reamer is available from who?

[seaboltm]

I don't know of anyone who stocks such a reamer. I am sure one could be built. I very, very seriously doubt an improved 7.62x39 cartridge will give you anywhere near 3000 fps. Its the rule of 1/4. Lets say you increase case capacity by 20%, the rule of 1/4 says you get a 5% increase in velocity. Improved cartridges gain their extra velocity due to hand loaders loading to higher pressure. The velocity increase due to case capacity increase is minimal.

[43PU]

i have a 7.62x38 improved (when you improve it you loose 1mm) I can get the lee 312-155 powder coated to around 2800 FPS with GREAT accuracy I built it in a AR platform

43PU

[Doc Highwall]

If I was going to improve it I would just rechamber it to 30 BR. which would give me the extra case capacity with standard dies and use Lupua brass. Also there is plenty of reloading data for the 30 BR using cast bullets.

[Vinne]

There is only so much that can be done with that round. Now if you replace the barrel and neck it down to 22 cal then maybe you can pump it up more but that is a lot of work for a cartridge that is fine the way it is. If you want more then just go out and get a magnum cartridge. Just me!!!

[GhostHawk]

Funny I went the other way. I took away the jword, put in a 185 gr cast boolit with gas check instead. Lowered powder charge accordingly.

So it is about 1/3 slower, but at the other end because I increased boolit weight it hits with similar total energy as the factory loads.
With a fairly slow rifle powder (IMR 4895) it was knocking the paint off the back side of my target gong.

Faster is not always better. I know a lot of people chase that rabbit, but its not the only way to go.

[cz22khornet]

It is actually a very good idea since the Little Russian case has quite a bit of taper. I did extensive reloading and shooting with this cartridge in the CZ 527 Carbine using cast and jacketed bullets. I found that when I started to use heavy cast bullets (~200 grain or higher) I would get misfires. I believe this was because of the very limited shoulder on the 7.62 x 39 not being adequate for handling the inertia generated by the impact of the firing pin on the heavy cast loaded cartridge. Improving it would give you a better shoulder to work with and might improve reliability.

I also hunted with it one season using a hand-loaded Barnes X-bullet. That season I shot a 165 pound buck at about 80 yards. I could tell the bullet definitely did not have any noticeable shock effect when it hit the deer. Also, after recovering the bullet I noticed that the X-bullet's petals were not fully opened. I think this was because the velocity was not high enough.

My conclusion then and now is that the cartridge could benefit from an Ackley shoulder, greater powder capacity, and higher velocity.

[Artful]

Russian's did improve it - not as 30 caliber but 9mm

Notice they removed taper but to increase penetration they went with a larger projectile

http://en.wikipedia.org/wiki/9%C3%9739mm

SP-5 (7N8) - The SP-5 (СП-5) (SP: Spetsialnyj Patron; "Special Cartridge") was developed by Nikolai Zabelin. It is a conventional lead core FMJ bullet, but developed for accuracy.
SP-5UZ - The SP-5UZ (СП5-УЗ) is an SP-5 variant with an increased charge intended for a factory-specific strength testing of the weapons.
SP-6 (7N9) - The SP-6 (СП-6) was developed by Yuri Frolov. It has a hardened metal armor piercing core. It can penetrate 2 mm (0.079 in) of steel at 500 meters or 6 mm (0.24 in)of steel, 2.8 mm (0.11 in) of titanium or 30 layers of Kevlar at 200 meters. At 100 meters it penetrates 8 mm (0.31 in) of steel, while retaining enough power to neutralize a soft target behind it.
SP-6UCh - The SP-6UCh (СП-6УЧ) is an SP-6 variant intended for training.
PAB-9 (7N12) - The SP-6's bullet is expensive, so an attempt was made to make a lower-cost version of the cartridge. The PAB-9 (ПАБ-9) used a stamped rather than machined steel core. It sacrificed too much performance to be usable. As of 2011, its usage is prohibited.^[2]
SPP - The SPP (СПП) (SPP: Snaiperskie Povishennaya Probivaemost; "Sniper - Increased Penetration") is a sniper round with an increased penetration.
BP - The BP (БП) (BP: Broneboin'ie Pulya; "Armor-Piercing Bullet") is an armor-piercing round.

used mainly in weapons like
Vintorez 9×39 Sniper Rifle

http://www.sadefensejournal.com/wp/?p=372


http://www.liveleak.com/view?i=ffa_1297051976

[Bullshop Junior]

Basically a 35 Remington short.

[Larry Gibson]

If you "improve" the 7.62x39 case you end up with right at 30-30 cases capacity. Not enough for 3000 fps even at the PMAP of 51,500 psi for the M43 cartridge and certainly not at the PMAP for the 30-30. However, with 170 gr cast bullets (314-041) over a fire formed and NS'd R-P case full of LeveRevolution (31 gr) I get 2076 fps out of my 20" barreled Mini Mk X Mauser. Held 2" at 100 yards for 10 shots which is about as good as the rifle will do with the 4X scope and as light as it is. Great load and a great little rifle.

Larry Gibson

Attachment 118302

[nekshot]

very interesting info here for sure. I am not trying to make a 308 out of it just seeing how much you can get by improving. I had my doubts with those Barnes bullets and the slower speed and we us alot of Barnes for deer and love em. My only gun with this round is a carcano and I shoot only cast in it and thanks to Larry testing LVR I have alittle more oomph for the round. I really need to get rid of some stuff and get a cz or a mauser action. Simply put and I am not crying about this but 15 lbs is all I can handle with out going into intense pain so I am trying to lighten the load and I enjoy staying in my stand all day if need be so it takes a little more loot to haul then just sitting 5 minutes walk away from the vehicle.
Thanks for all the info.
Art, that is very interesting.
Bullshop jr, I just put together another carcano in 35 remington and with scope weighs 6 and 1\2 pounds. Will be a kicker for sure!

[dougader]

I was looking at the 300 BLK just yesterday and wondering why a 7.62x39mm Improved wouldn't make a better case for both supersonic and subsonic loads. It would get rid of the extreme case taper and supply a little extra oomph for deer hunting with supersonic loads, or even heavy cast bullet hp's at subsonic velocities.

I was thinking maybe a 7.62x39 Ruger Ranch rifle or similar could be rechambered or even an upper for an AR15. The straighter case would get rid of those ultra curved banana mags on AR's and maybe feed a little better?

[Mauser 98K]

i did improve it. i made hollow point hunting bullets that would actually mushroom, unlike the **** you get commercially that slightly deforms or punches all the way through like an ice pick..

[43PU]

I built a 20” upper with a improved, I get low end 308 ballistics with it

[nekshot]

Hey, You got my attention! Love to have more info if you don't mind. Like where did you get the reamer, dies or did you make em?

[Harter66]

I believe the 30 Herett rimless is what you seek .

In an AR platform you can go long to the 6.8 case or the x39 or you can keep the 556/223 bolt and use the 22 Nosler case which is a rebated rim to the 223/556 rim on the 6.8/30 Rem case . I suppose the same could be done with a bolt gun . The best bet overall would be to use a blued or stainless barreled 300 BO and an interchangable floating pilot reamer on a 6mm ppc if you don't want the 30 Herett rimless .

AR Performance has 30 Herett barrels with matched bolts available .

[Texas by God]

How can that little case produce "close to 2800" fps with a 155gr boolit? I'm pretty sure it can't. These "mildcats" that pop up weekly in the AR world seem to have some hot air in their numbers- not unlike the old "wildcats" based on larger cases in the 1950s and 60s.

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[Harter66]

I personally Chronyed a 200 gr cast spire point very similar to the NOE 311-230 with a shorter shank . Loaded mag length in the SKS in a 7.62x39 with a .305x.316 barrel paper patched to .318 with 22.0 I4350 and they consistently ran 1620-1640 moving it up to a single load only and 25.0 it went 1795-1810 fps .
First I recognize that I had a 24" barrel to burn the sloooww powder in but at mag length and 19.0 it didn't burn clean . In fact the mummies only went away at 21.5 gr and 24.0 in the single feed rounds .

The 7.62×39 is rated at up to 2200 fps with 150s and to 40,000 CUP , it's a 48,000 psi rated cartridge , with jacketed bullets and H322 and 4895 .
I also realize that there are only like 6 cases where PSI and CUP intersect as the same values .
The AR platform with a 7.62×39 compatible bolt is a 62 kpsi rated lock up .
Stay with me .
We only need to look at a hand full of other cartridges like the 30 Luger vs the 7.62 x 25 TOK and 38 vs 357 to see what can be done with 10,000 psi .
The Luger into TOK gains 500 fps with a 90 gr bullet and the 357 gains up to 500 with a 158 gr bullet . Now with the case , a x39 increased to PPC case volume from the original and 10kpsi I don't see any reason why a 7.62×39 AI can't deliver 2600 with a 150 . Backed down to a 120-125 standard data for the 6.8 allows for 2600 fps at 58kps while the x39 promised 2400+ with a 123 at just 44kpsi . Bigger hole faster powder or the same powder and reduced pressures and the speeds aren't all that far off .
Increased pressure ratings are why the 308 matches the 06' with bullets up to 150 gr in a case a half an inch shorter .

[Texas by God]

That's a good explanation but my 30-30 won't propel a 150gr 2800 fps so how can a x39 Imp do it?
The answer is- it can't. Load the 30-06 to the same pressure as the .308 and see what happens.
I'm not starting an argument I just speak up when I see something questionable.
Thomas

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[Mauser 98K]

Hey, You got my attention! Love to have more info if you don't mind. Like where did you get the reamer, dies or did you make em?

if ya was talking to me, i made my dies.. if you could get it to work i suppose any swaging setup could make them.. the jackets are almost pure copper sheet, 0.020in-0.025in thick copper flashing drawn to cups. they are annealed so very soft. the core is pretty much pure so it is very malleable. they are 130gr and the tip is closed to about 1/8in diameter. im using H-322 loaded to about 2,200fps.