The 300 blk out WILL need a suppressor to get it to cycle and AR. There's not enough pressure otherwise. The Sub-X bullets I've seen pictures of recovered from animals had minimal expansion, if any at all. Plus, on the scale of velocity, they are slower in velocity than most subs. They often run 850-950 fps, where you can get up to about 1050 fps and still be safely subsonic. And if you run a short barrel, they will be even slower.

Sounds like Hornady's marketing department got a bit ahead of themselves! It happens all the time; and the poor old techs are left with explaining why the products don't perform as advertised! Thanks for the heads-up, Chad.