I have tended to, incorrectly, use the milspec term, for items used by the military. The Blackout cartridge box is interesting in that there is not even a CAGE code on it. Barnes is owned by Remington, and they have a CAGE code.
Having seen *true* Milspec ammo boxes of 300 Win Mag, 7.62 Long Range, my earlier assumption was wrong, that the 300 Blk was the same.
I find it interesting some of the cartridges that are being used/tested by the military. One of the surprises to me, was the 300PRC. I wouldn't think the 300PRC would be Milspec either. The snipers are mainly using the Mk13 Mod7 in 300 Win Mag. But there are some 300PRC rifles being tested to try stretch out the range of the "smaller" bores. There are 338 Lapuas and McMillans in 50 caliber in inventory, but a 30 caliber would have less recoil.
Tom In Va.