...The biggest problem comes in keeping enough of them cast and lubed, once one discovers how much fun they are to shoot.
You should have no problem loading the 7.62x39 to sub-sonic velocities. As you are loading for a bolt gun, you have no worry's with over all length. That is the usual problem with heavy bullets in this caliber. They stick out too far to feed from the magazine of rifles chambered for it. I have shot some 180 grainers from my SKS, had to single load them, but they seemed very accurate. Unfortunately, I haven't made any since I got my chronograph. Guess I'll have to now. :-)
There are a lot of good powders that will work, you might need to stay with the faster powders though. Small case, big bullet. I'd try for maximum case density to insure that it all burns.
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