I've been working with CE Harris two articles on “CAST BULLET LOADS FOR MILITARY RIFLES” and a post he did specifically for the 7.63x39.
I'm using the Lee C312-155-2R. I use 50/50 lube and run it through a .313 sizer mostly to lube and install the Horanday gas checks - the bullets don't usually get sized much.
I've got my Norinco SKS working great. I started to get it to cycle at just over 12.5 grains of Alliant 2400 and seemed to work better as I approached just under 14. So, I loaded up a supply at 14.5 since I'd be doing some cold weather shooting as well.
I just got a Yugo SKS. The 14.5 won't cycle it - they don't even stovepipe. The action opens just a bit. This load chronys at just about 1,700. The Wolfe 122 grain FMJ works this action fine and chronys at about 2350+.
In one article Harris suggests that the max load of 2400 in the 762x39 case should be 16. Then, he had an update to a post in 2008 suggesting not to exceed 15. I doubt that 15 will do it for me - and I'm not sure even 16 will work.
His addition to the one post says:
"Most up to date info from Ed Harris - 2008 Quote: In the SKS start with 11 grs. of #2400 and increase the load gradually until you get reliable function. Do not exceed 15 grains of #2400. You can work similarly within the range of 13-18 grs. of 4227, 16-22 grs. of 4198, 18-24 grs. of RL-7"
So, my quesitons start off here:
Should I limit the 2400 to 15 grains - in which case I should rule this out for this gun. Or should I try it up to 16 - in that case I'm skeptical but it might just work.
Then, assuming the 2400 wont work - would some of the other powders he suggests here such as 4227, 4198, or RL-7 make a difference? Of them all, I'd like to try the RL-7 first. Do I just start at the lowest charge knowing that the max of 2400 does not work - or could I start at mid-range charges?
If I were to get to whatever the max is on 2400, I'm trying to understand why another powder would work without also being over maximum.