Follow the money. The cost to switch this completely will make someone(s) very rich. Whereas the transition to 300 blackout by changing only barrels and magazines would not enrich some retired generals yet be a much more viable transition with much reduced recoil and barrel lives.
Wow.
Do you realize what the range of a 300 blackout is? I hunt deer with a suppressed 300 blackout so I can tell you....about 80 yards. Beyond that it falls apart and is practically useless, yet you want to replace the entire inventory of infantry rifles with it? I want to be on the side of whoever's fighting you when the next war breaks out.
The 300 blackout kicks about the same as the 5.56, which is practically none in either case. Barrel life is a non-issue, if you can wear out a 5.56 barrel or a 300 blackout barrel then you've shot 1000X more than the average soldier will shoot in his career. I'm on my fourth 22-250 barrel after shooting untold thousands of rounds at prairie dogs and it's not particularly a barrel burner round. If you want to wear out a barrel load a 220 swift to the hilt and shoot it until the barrel almost glows. You're not going to wear out a chrome lined military M16/M4 barrel in your or my lifetime, and I doubt anyone will be able to wear out a barrel of the new round. It's a non issue.
300 AAC or blackout cannot penetrate level 4 armor it lacks the energy even at the muzzle. Neither can any of the 5.56 black tip rounds. The whole reason to go up to a 6.8mm sized bullet is it carries the kinetic energy needed to 600 meters to penetrate level 4 armor. This is also why you need 80,000 psi if you want to use a shorter barreled rifle. As was pointed out this also has a gas piston not the crap self impingment. Finally the infantry gets a real battle rifle not the toy sized M4. Anyone who has ever lit off a M14 in full auto knows that rifle means business. This round trumps the 7.62x51 mm by a good bit it should be a stone cold man killer with the streamlined 6.8 mm and fast twist rate you can send sleek high BC bullets waaaaaaaayyyy out there the 6.5 creedmore stays supersonic to nearly a mile and this round adds 30% more bang that a creedmore. To bad at 80k psi you have to use steel cases which means no reloading. The military doesn’t care about reloading every round is a single use item always has been. Used military brass is never reloaded by the military they gather it up in training and sell it for scrap. The Russians and the Chinese have used steel cases exclusively for decades they don’t even bother to field brass cases ammo steel is cheaper.