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    • #27428
      reloader762
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      A gentlemen on another board posed a question about the lack of available cast lead gas check bullets moulds in the 123 to 125 gr. range for the 7.62 x 39. I know Lyman make a 115 gr.GC as well as a 130 gr.PB both of which are .311″ dia. an NOE has a .314″ 129 gr. GC version but it’s been out of inventory for awhile.

      His main question is why are most of the available mould designs in the 150 to 160+ gr. range instead of the traditional bullet weights found in factory jacket bullet loadings. Is there a disadvantage to those shorter lighter weight bullets in the SKS over the heavier available bullets. I’ve done a good bit of research and couldn’t really find any info on why the lighter weight cast bullets or moulds aren’t available.

    • #27429
      GhostHawk
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      By rights they should be available.

      At the same time, when I got my Yugo SKS, and went through this, I already had both the lee .312 155 gc and the .312 185 gc molds. So those are what I started experimenting with. What I learned is that a .312 185 gr gas checked boolit of fairly low BH (range lead sweatened with a bit of tin) over 20 grains of IMR 4895 shot to point of aim at 50 yards consistently, and hit like a kick from a mule. I have shot my AR500 target gong with lots of different rifles. But the SKS is the only one that can tip it over at will with 2 well timed shots.

      Being heavy for the caliber, I started low on the charge, and by the time I had the bore shot and cleaned and shot till it shines I could see no reason to change it.
      Your mileage may vary.

    • #27431
      Rattlesnake Charlie
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      Right up front, I’ll tell all that I have never loaded for the 7.62×39.

      It is my thought that by using a cast boolit heavier than the normal jacketed projectiles, you could get the gun to cycle reliably while keeping the velocity down to a point where it is not too difficult to prevent leading and still get reasonable accuracy. I read about the same principle in loading for the Garand.

      Just a possibility. May not be true. But, it might be.

    • #27432
      reloader762
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      I started out with the Lee .312″ 160 gr. RN gas check boolit myself,I’ve been shooting that one for probably eight or nine years behind 14.5 grs. of Alliant 2400 or 18.0 grs. of Reloader #7 as my go to loads. My Chinese SKS will cycle with a load as low as 12.5 gr. of 2400 all day long with the Lee boolit. I just picked up a new NOE 155 gr. .314″ GC RNFP to try out in my SKS and Mosin rifles. I like the heavy for caliber boolits myself.

    • #27435
      Goodsteel
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      Just a thought, rather than looking at bullet weight, maybe you aught to look at bullet length.
      The twist rate is designed to perform with a certain length projectile.

    • #27436
      Artful
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      Oh, they are available – just not that narrow a range

      I’ve got a NOE mold in

      – RCBS makes one in that range

      – Lyman makes 311359

      Lee doesn’t really offer one but but
      frankly their rendering of the Ed Harris design at 155 to 160 grain shoot so well that I don’t
      see them really needing to come up with a new design – if you want it less pointed get the NOE
      version – NEI makes one as well

      but since Walt Melander passed I have not ordered any from them
      and have not seen any recent reports as to quality.

    • #27437
      Larry Gibson
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      reloader762

      Rattlesnake Charlie hit the nail on the head with; “you could get the gun to cycle reliably while keeping the velocity down to a point where it is not too difficult to prevent leading and still get reasonable accuracy

      Almost all 7.62x39s have 10″ twist barrels. New commercial rifles follow the Russians lead using 10″ twist barrels also. With the 10″ twist the RPM threshold is going to be between 1900 and 2000 fps with nominal cast bullets for use in the 7.62×39 cartridge. That is with GC’d cast bullets of 100 to 190 gr. Thus driving a 123 – 125 gr cast bullet to the SKS/AK velocity of 2250 – 2350 fps pust that weight of cast bullet way over the RPM threshold to the point that accuracy is very poor if no existent.

      I have done considerable testing of lighter weight GC’d cast bullets in my Russian SKS and my Mini Mk X Mauser. I have tested the 313631 (105 gr SWC), the 311359 (115 and 122 gr) and the 311465 (124 gr) in both rifles. I have found all give excellent accuracy through 1900 fps in the bolt gun and to the same velocity in the SKS with functioning loads if a functioning load could be found while keeping the velocity under 1900 fps. In the SKS finding a functioning load with any 120 gr or less cast bullet under 1900 fps was a crap shoot at best and I did not find any I would call “reliable” as to functioning. Above 1900 fps the 311465 (older Lyman mould that drops 122 gr COWW + 2% tin alloyed bullets at .312- .313 which weigh 124 gr fully dressed) at around 2100 – 2200 fps I could get 4 – 5 moa accuracy (10 shots at 100 yards) which equals most milsurp accuracy. However, at 200 yards the load was hard pressed to stay on an E target (19.5 wide by 40″ tall). Frankly the bolt action Mini Mk X did not fare any better when the lighter cast bullets were pushed beyond 1900 – 2000 fps.

      With 150 – 190 gr cast bullet the velocity with medium burning powders (I prefer H4895 or LeveRevolution with them) Normal top end loads are in the 1700 – 1950 fps range. That puts them right in the “accuracy zone” for use with cast bullets in 10″ twist barrels. Unless pushed to the max with LeveRevolution powder they do not exceed the RPM Threshold and accuracy is usually excellent, especially in a well bedded SKS in excellent condition. Thus we see the reason for the popularity of the Harris designed Lee C312-150-1R cast bullet. It gives reliable functioning in the SKS/AK actions while maintaining a velocity below the RPM Threshold.

      Goodsteel finished driving the nail in with; “rather than looking at bullet weight, maybe you aught to look at bullet length.
      The twist rate is designed to perform with a certain length projectile
      “.

      When the Russians designed and adopted the M43 cartridge (7.62×39) it was specified to be used in the standard barrel the Russians were turning out since 1891 for their 7.62x54R cartridge. They saw no reason to use any other barrel twist to further complicate manufacture since, with jacketed bullets, the M43 cartridge performed to specifications of accuracy using the standard 10″ twist barrel being used for the larger cartridge. The SKS, RPD and then the AK47 were designed around the cartridge. The 7.62x54R cartridges barrel was designed and adopted in 1891 for use with a 220 gr bullet (the same as our own 30 Gvmt cartridge). That is the reason for the fast 10″ twist in the 7.62×39 barrels; the Russians were making those barrels by the bajillions and saw no reason to use anything else.

      I’ve been thinking that when (if I ever do) completely shoot the throat out in Dawn’s barrel (16″ twist in 30×60 XCB) there should be enough of the 31″ barrel left with very good lands and grooves to put a 22 – 24″ heavy barrel on the Mini Mk X Mauser. The 16″ twist with the 7.62×39 cartridge should make it just about optimum for use with the 115 – 125 gr cast bullets to the full potential velocity of the cartridge. That should be around 2500 fps with a 22 – 24″ barrel………just cogitating……..

      Larry Gibson

    • #27438
      Smoke4320
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      excellent answer .. much good info in that post

      Thanks

    • #27448
      reloader762
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      Thanks guys I appreciate all the great info an although I wasn’t really asking the question for myself since I’ve had great success with my own cast bullets in my SKS rifles I did learn some technical aspects that are good to know and I will be printing them off and adding them to my own personal load data binder. I will also direct the gentleman to these post to read for himself as I believe it will answer his questions.

    • #27449
      chutesnreloads
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      Glad I’m not the only one who makes hard copies of the really good posts.Who knows….someday the interweb could just go pfffft.Imagine all this great information lost or at least not as easily accessible

    • #27450
      reloader762
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      chutesnreloads;n6351 wrote: Glad I’m not the only one who makes hard copies of the really good posts.Who knows….someday the interweb could just go pfffft.Imagine all this great information lost or at least not as easily accessible

      Exactly,my binder is probably four inches thick at the moment and is sectioned off for each rifle and pistol caliber I handload for. I keep back to back pages in plastic sleeves with all the current commercial data as well as all my own load data and any topics of interest I find on the net that may be of use later on.

    • #27451
      Goodsteel
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      Larry Gibson;n6337 wrote:
      I’ve been thinking that when (if I ever do) completely shoot the throat out in Dawn’s barrel (16″ twist in 30×60 XCB) there should be enough of the 31″ barrel left with very good lands and grooves to put a 22 – 24″ heavy barrel on the Mini Mk X Mauser. The 16″ twist with the 7.62×39 cartridge should make it just about optimum for use with the 115 – 125 gr cast bullets to the full potential velocity of the cartridge. That should be around 2500 fps with a 22 – 24″ barrel………just cogitating……..

      Larry Gibson

      We can set back and put it back in Dawn
      Then we set it back for the Mark X……..twice.
      Then we make an AR barrel out of it.
      Then a Contender…….twice.
      Then we cut the last 4″ off and make a seating die out of it.

      That’s what I call barrel economy! Play your cards right, and that could be the cheapest barrel you ever bought.
      LOL!

    • #27789
      Rattlesnake Charlie
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      Has NOE’s 311465 been tried in the 7.62×39?

      How about the 311410?

    • #27792
      Larry Gibson
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      I just happen to have NOE’s 311465…….just might have to give it a try in the Mini MK X and SKS…………

      Larry Gibson

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