
Not sure on specs or what they changed, but I do know they had modified it well out of normal specs. Description Atomic Subsonic 223 Remington Low Recoil, Reduced Noise 77 Grain Hollow Point Boat Tail 50 Rounds NOTE: This ammunition is not specifically designed to cycle semi or fully automatic weapons. Receives squad leaders requests for rations, water, and ammunition. SilentStrike is the worlds only Jacketed Frangible Subsonic Ammo. Have your musket clean as a whistle, hatchet scoured, sixty rounds powder and ball. with the slide lock, the Mk22 fired heavy subsonic 158-grain bullets known as. Allegiance uses a compressed, powdered-metal core giving it the ability to penetrate. I think it would be grossly overgassed with normal ammo, probably beating itself up a bit. that when a human being is struck by a rifle bullet, two things happen. But the entire gas system on that Beck gun was highly modified so it would cycle the subsonic ammo. These barrels obviously have tight twist rates for the heavier, slower bullets and, from the sounds of it, perhaps a longer throat to clear larger projectiles and maybe a modified gas port (although it doesn’t look vastly oversized in the photos and, if the ammo really cycles a standard AR, it wouldn’t have to be oversized). Their flagship PowerStrike ammo is built to penetrate thick hide or clothing and then dump all of its energy into the target. One thing I did notice is that Allegiance claims their subsonic ammo runs a totally standard AR-15. It is quieter than most 22 long rifle ammo, has virtually no felt recoil, produces the same energy and power as most 380 ACP ammunition and delivers excellent accuracy out to 100 yd from rifles with barrel twist rates of 1:7 inches or faster.

But there’s no reason these Allegiance ones wouldn’t also work with normal ammo, and the text of their press release makes that pretty clear: “Coming soon the Allegiance subsonic barrel designed for subsonic and supersonic ammunition.” Atomic Ammunition's 223 Remington Subsonic is unlike any 223 Remington ammunition.

I’ve shot those Beck guns myself (video of the subsonic: ).
