“This is good for both the two legged and four legged varieties? Or should I just stick with my 7.62x39?”
The 300 AAC advantage would only be in using 220 grain bullets at sub-sonic velocities. The rifling twist of one turn in 8” allows you to use those heavier bullets. So unless you want to use a silencer and not have the bullet break the sound barrier stick with your 7.62x39.
I’ve got allot of friends that use the blackout for nightime hog hunting where the distance is 50 yards or shorter and they all say the same thing. The twist needed for the sub sonic rounds will not work for the higher velocity rounds so you need two dedicated uppers for your AR’s.