Geez what's with all the hate? Conceptually no different than a .300 Blackout which every operator wannabe is jumping all over these days. When you're dealing with subsonic velocities, you want to be throwing the heaviest bullet you can to maximize energy. This round appears to do that.
However...
In your first post you said it has a flat trajectory. So which is it?
Well there is a key difference, or two.
The .300 BLK uses a standard AR 5.56 bolt.
This abomination will use a 7.62x39 bolt, which are both harder to find, but more importantly, prone to breaking due to the wider base of the cartridge requiring less material be used on the bolt.
Also, not sure of the mag this will use, but if it's not a standard AR mag like the .300 BLK, then that's another major difference.
And lastly, AAC never claimed the .300 BLK has a "flat" trajectory.


















































