(Ack, that 125 Gr is little better than a 30-30, not much so. I make my own 150Gr Sp on a Winchester case with 27 Gr of 4895. The ballistics puts it within the low 308 power. One of the sponsors has factory made 150 Gr but the shipping was pricey for my area of NB.)
“WHAT” you can get enough powder in a 7.62X39 case to duplicate 308 velocities. I think NOT. The listed velocity of 308 Win factory 150 gr. is 2840 fps. And the Hornady hi velocity is 150 fps faster.