Since no one replied I'll put in a opinion....
I use the C.E. Harris 160 from Lee mostly in my SKS.
With Unique, I run about 4 gr. and cycle
each one in by hand, no gas check, cheep shoot'n..
I like 2400 or 1680, it starts running semi and about 14 gr with the Harris 160 gr --(thought help on this board) but have not got the Patten I'd like yet..
I 'm sorry but I haven't worked with 120 gr lead more then a little plinking at about 4 gr of Unique ...fun - low noise shoot'n
I have a 311465 122 gr mold,, so I would like to hear how thing are working with your SKS....
I think that a SKS is a good cast bullet gun --if you don't shoot it as fast as it can to empty the magazine ------- slow down and have fun DAN