Yeah, amazing that some think that AAC built this from the ground up, they stole a design already out there.
Not that it matters... my dies still say 300/221 FWIW... LOL.
Now to teh question.
If you are shooting super sonic, then 7.62x39 hands down over the 300/221. Why anyone would use a 300/221 with its hassles when you can go the X39 is beyond me.....
Going subsonic brings up a few things though. Fast enough twist for the heavy bullets... 240s may need 7 and not 8....
You will have a LOT of action noise in the AR, and why I was going to put a gas block on I could turn off for deer hunting when I want as quiet as I can and follow up shots are not a big deal... and then I bought a 700....
But subsonic for pigs and the like, you have to deal with action noise regardless if you want follow up shots.
I can say this much, putting a suppressor on a 22, I hate it that I had a 10-22 because half the noise is the action slap.... searching to buy the right bolt gun for the 22 now...
But remember supersonic use... x39 has a lot of brass out there, no need to form, cheap enough.... lots of bullets that already work fine... 125 ballistic tip is made for the round IMHO in the AR. And the possible use of surplus if not at least cheap blasting wolf type ammo.... I'd never run the 300/221 supersonic on purpose....
