The other comment I would make, though, is I read the .300 is the equal of the 7.62x39. I'll say, not exactly - since the Rooskie round will drive 123's as fast as the .300 will run 110's.
300 BLK has 16.7% more energy than 7.62x39mm at 300 meters. There is not a single 7.62x39mm factory load which is more powerful than 300 BLK past 120 yards. I have posted much proof of this before, along with photos, but it is a pain to re-locate this stuff that I have said in the past each time it comes up.
