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Discussion Starter · #1 ·
Is there a 7.62X39 Improved cartridge? This is simlpy the parent with a 30 degree shoulder matching the angle for the 22 and 6MM PPC, but not pushing the shoulder back.

The 7.62X39 is one of my favorite cartridges to reload, because the industry specs call for a max of 50,000 CUP while factory loads are held to the 40-44,000 CUP range in deference to the AK and SKS actions out there. I load mine for a CZ Carbine bolt gun with 18 inch bbl and easily generate 2000 FPE with 130 gr Hornady PSPs @ 2650 fps. That's good for 2130 fps and 1300 FPE at 200 yards and a 4.9-inch drop sighted in at 100 yards.

2800 fps is within reach of this case, improved to hold 33 grs of water with a seated 125 or 130-gr bullet. Coupled with a 1 in 14-inch twist, this is a 0.25 MOA round. Most 7.62X39 rifles are 1 in 10 or less, which is way too fast for .308 to .311 bullets less than an inch in length. Might as well design it for a .308 bbl while we are at it. Think of it as a .308 Win with a 1-inch powder column length, designed to shoot bullets less than 1 inch in length.

I also use sabots and 55-gr .224 Hornady BTs in the 7.62X39, with remarkable results. Lil'gun easily drives these to 3500 fps and delivers 1.0 MOA. Pressure is moderate. Note that this is well over a .223 and close on the heels of a 22-250. The improved version will duplicate the 22-250. However, the suggested 1 in 14 twist would limit us to .224s lighter and shorter than the 55-gr spitzers. A 45 gr BT will do 4000 fps, guaranteed.

In the end you have a neat little rifle, 5 lbs in weight with 18 inch bbl and 2.3 inch bolt throw, covering varmints through deer, that is inexpensive and fun to shoot. You win the lightweight hunter class at your range every year and your bore and shoulder last forever.
 

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Discussion Starter · #5 ·
I am thinking that the 35x39s must be improved, as there is not enough shoulder to headspace. I do shoot a number of .312 pistol bullets out of it and get 2750 fps with 100 gr HPs. Good devastating varmint round. The .314 lead balls @ 1400 fps are fun too.
 

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Discussion Starter · #13 ·
Remington's Accelerators operated at 38,000 CUP, far below max. The problem is that there is no off the shelf powder that can burn progressively with such a light projectile in a big bore. Pressure drops like a stone as the light mass accelerates in the big bore.

If there were, you would get the same energy out of the light bullet as a heavy one. The 7.62X39 loaded to 50,000 CUP with R7 and a 123 PSP will do 2600 fPS for 1845 FPE. This energy with a 50 grain bullet is 4074 fps, its just that no off the shelf powder will do it.

Since we can't make powder at home, we need to make sabots and use heavier bullets. I have mine made by a local injection molding firm, and had great success with bullets 80 to 85% of the diameter of the bore with bore sectional densities not less than .150. The increased weight slows acceleration a lot, and allows the use of off the shelf powders.

If you stay within this envelope and use good materials for the sabot, you can get muzzle energies that equal to the parent cartridge. For example, an '06 will generate 2750 FPE with a 180 gr bullet, and will also do the same thing with a 100 gr 6MM bullet in a .308 Sabot. This is 3518 fps at 48,000 CUP.

I now have graduated to the 375 RUM which launches 180 gr .308 Noslers at 3675 fps at 60,000 psi.



Duplex might do it, or possibly a specially designed powder. Longshot is too fast, but it has the right characteristics.
 

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Discussion Starter · #18 ·
Oh, dear....the 7.62X39 Stanton has 31 grs of water case capacity and will drive a 135 gr bullet 2650 fps. This bullet has a SD of .203 and matches the trajectory of the new Remington .277 military round.

Wonder how much they spent on THAT one? I figure the average soldier will take the weapon that also shoots 7.62X39 given a choice. The improved round aslo solves the problem we have with feeding the 7.62X39 into the AR15 action.
 

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Discussion Starter · #20 ·
Oh Drat...now I really can't stop thinking...a 110 gr Hornady PSP adds 2 grs of case capacity and will do 3000 fps in the 7.62 Stanton. We gotta build one of these and have a friendly little match with thr REM.
 

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Discussion Starter · #22 ·
There is a 358X1.5 based on the great 308X1.5 developed by Frank Barnes. These may be made by simply necking up the 7BR.

The 358X1.5 is actually a powerful cartridge capable of developing over 2500 FPE with a 180 gr Speer at 2525 fps or a 200 gr Hornady at 2400 fps.
 
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