7.62x39 reloading 20 inch vs. 16 inch barrel powders

BigDanSBigDanS Senior MemberPosts: 6,807 Senior Member
Now that I am getting ready to reload my 7.62x39's I can see where this can become obsesive. While loading for the 30-06 might be well figured out, loading for the 7.62x39 is a bit more up in the air.

I now have the Lyman, Hornady, Sierra and Lee reloading manuals. Lyman tested their loads from a "standard receiver" with a 24 inch barrel, Sierra from a Mini 30 with a .308 barrel, Hornady from a 20 inch SKS, and Lee lists no gun at all. To top it all off you have them testing .308 and .310 and .311 bullets in various weights from 110 gr to 154gr. Although Hornady tested from a 20 inch SKS they did not test 150 / 154 gr loads.

I have two SKS's ( realistically I have several more but this is what I want to discuss ) , one with a 20 inch barrel and one with a 16.5 inch barrel. There appears to be a range of powders suitable for the .311 diameter barrels and projectiles, from:

Accurate Arms 5744 fast
Accurate Arms 1680
NORMA 200
Alliant Reloder 7
IMR, Co IMR 4198
Hodgdon H4198
VihtaVuori N120
Hodgdon H322
Accurate Arms 2015BR
Alliant Reloder 10X
VihtaVuori N130
IMR, Co IMR 3031
VihtaVuori N133
Hodgdon BENCHMARK
Hodgdon H335 slow

My reasearch shows the fastest tested loads are with H335 and 125 gr bullets, yielding 2400 FPS and about 1600 FPE from a 20 inch gun. H322 was best in a 20 inch gun with 150 gr projectiles. I also see Vit N130 / N120 being listed as the best for accuracy in one of my books.

If you consider this information, and want to load specifically for a shorter barreled gun, do you look for a faster burning powder? Will this help get better velocity from a shorter barrel?

Specifically I am considering loading .311 150 gr Sierra model 2300 spitzer bullets for hunting and accuracy, that have a sectional density of .222 and a BC of .341. I anticipate being able to get 2100 FPS that should yield almost 1470 FPE.

Additional research shows people really like Reloader 7 and AA1680

I am considering using AA 2015 BR in my 16.5 inch gun as it burns right between V 120 and V130 and has a reputation for consistancy.

Any thoughts before I blow myself up?

D
"A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:

Replies

  • snake284snake284 Senior Member Posts: 21,909 Senior Member
    BigDanS wrote: »
    Now that I am getting ready to reload my 7.62x39's I can see where this can become obsesive. While loading for the 30-06 might be well figured out, loading for the 7.62x39 is a bit more up in the air.

    I now have the Lyman, Hornady, Sierra and Lee reloading manuals. Lyman tested their loads from a "standard receiver" with a 24 inch barrel, Sierra from a Mini 30 with a .308 barrel, Hornady from a 20 inch SKS, and Lee lists no gun at all. To top it all off you have them testing .308 and .310 and .311 bullets in various weights from 110 gr to 154gr. Although Hornady tested from a 20 inch SKS they did not test 150 / 154 gr loads.

    I have two SKS's ( realistically I have several more but this is what I want to discuss ) , one with a 20 inch barrel and one with a 16.5 inch barrel. There appears to be a range of powders suitable for the .311 diameter barrels and projectiles, from:

    Accurate Arms 5744 fast
    Accurate Arms 1680
    NORMA 200
    Alliant Reloder 7
    IMR, Co IMR 4198
    Hodgdon H4198
    VihtaVuori N120
    Hodgdon H322
    Accurate Arms 2015BR
    Alliant Reloder 10X
    VihtaVuori N130
    IMR, Co IMR 3031
    VihtaVuori N133
    Hodgdon BENCHMARK
    Hodgdon H335 slow

    My reasearch shows the fastest tested loads are with H335 and 125 gr bullets, yielding 2400 FPS and about 1600 FPE from a 20 inch gun. H322 was best in a 20 inch gun with 150 gr projectiles. I also see Vit N130 / N120 being listed as the best for accuracy in one of my books.

    If you consider this information, and want to load specifically for a shorter barreled gun, do you look for a faster burning powder? Will this help get better velocity from a shorter barrel?

    Specifically I am considering loading .311 150 gr Sierra model 2300 spitzer bullets for hunting and accuracy, that have a sectional density of .222 and a BC of .341. I anticipate being able to get 2100 FPS that should yield almost 1470 FPE.

    Additional research shows people really like Reloader 7 and AA1680

    I am considering using AA 2015 BR in my 16.5 inch gun as it burns right between V 120 and V130 and has a reputation for consistancy.

    Any thoughts before I blow myself up?

    D

    Dan If you have a 16 inch barrel version of the 7.62x39, I would load it up with some of the fastest of those powders and work from there. If you have the 20 inch barrel you still might do well with a faster powder for it. That's not a huge case and I think your faster powders will get you going with a better load.

    However, if you're concerned about pressure, I would be cautious as I usually am working up loads. When I tell about a load I worked up here, it makes no difference how wild it sounds, you can take it to the bank that I have worked it up to that level very conservatively. I have had some pressure problems when I first started loading and it scared the bejesus out of me. So I have been very conservative every since.

    Now that's not to say that I won't push the envelope on Velocities, that just means that when I get into a territory that makes me feel like I'm hangin by my toenails, I go very slowly and look for pressure signs at every step And believe me, I learned early on what to look for.

    Having said all that, I think you know where I'm going with this. I use a manual and even if it says a certain load was safe in the test barrel, I will go very cautiously toward that book maximum and if I see anything that tells me I might need to back off, I will.

    In the case of my .250 Savage with a 115 grain Combined Technologies bullet over RL 17 powder I didn't have any proven load data. However, I had been told by those who used RL 17 that if I went slowly, which I always do, I could probably get some surprising results. Well I sure did.. I won't publish this load again, because it sounded like BS to many here and I thought they were going to commit me to the State Hospital. But it was certifiably safe in my rifle because it took me months to get where I finally ended up woth it. But when I did, there is not a hint of excess pressure and this rifle is performing like something in a higher class.

    I think your 7.62x39 with the right powder is capable of really good performance with the right weight bullet, even in the shorter barrel. Just take your time and you will get there alive and in pretty good shape. I have seen others on here make bigger jumps in powder than I do, and I guess that's cool if they feel safe. I just like to go slowly and in small increments with a load until I feel it is worthy of its purpose or until I hit a level where I don't feel going farther would be safe.
    Daddy, what's an enabler?
    Son that's somebody with nothing to do with his time but keep me in trouble with mom.
  • TeachTeach Senior Member Posts: 18,429 Senior Member
    Job #1 on a SKS is to slug the bore and find out which bullet is more suitable. Drive a soft lead plug through the barrel with a mallet and a hardwood dowel rod, and measure the plug for bore size. A big split shot sinker slightly over bore diameter makes a handy sizing plug. Pushing .311" bullets down a .308" bore won't be disastrous, but you'll use up a lot of energy and lose some velocity swaging the bullet down to size if you've got a tight bore. Most 7.62X39 die sets come with two expander buttons so you can size the brass properly for either bullet.

    H335 is fast, and it should get a complete burn in the shorter barrel. It was the only powder I was able to use in the .257 Scooter to get up to that little case's full potential. Approach max loads carefully with that powder, however!
    Jerry
    Hide and wail in terror, Eloi- - - -We Morlocks are on the hunt!
    ASK-HOLE Someone who asks for advice and always does something opposite
  • timctimc Senior Member Posts: 6,684 Senior Member
    I agree a fairly fast powder for the shorter barrel and then load it up to the velocities of the 20" gun and you should see similar accuracy. This was my experience whne trying to use the same bullets in my 20" and 16" AR-10's. I was looosing a couple hundred fps on the shorter barreled rifle but once I pushed it back up to 2600 fps the accuracy came back in line with the 20" gun.
    timc - formerly known as timc on the last G&A forum and timc on the G&A forum before that and the G&A forum before that.....
    AKA: Former Founding Member
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