Is the difference in performance on deer due to the cartridge, bullet, or shot placement? You have not isolated the variables to the level that we can tell.
I can say, I have a bud who hunts with a 165 Hornady SST in a 308 Win. When he hits the deer behind the shoulder, they run off, and he does not find them till next morning, all eaten by coyotes. But, with the same rig, if he aims between the shoulder and neck, the deer goes down on the spot. The difference is, there is enough meat and bone to cause the bullet to upset in the neck/shoulder area. The rib shots just poke a hole.
When I hear a youtube presenter stating the bullet is going 500 fps faster than the Russian round, the only way to do that is a considerable increase in powder, or pressure. I did look at your internet data, and saw everything was 40 k psia, but I did not compare velocities to the Russian round.
