300 Blackout vs. Body Armor and Bulletproof Glass

Every time a new “gee whizz” rifle cartridge comes out, the curiosities about it can do begin to mount. One of the template questions is, “can it penetrate body armor”? While this curiosity is a novelty for most, 300 BLK serves its purpose among military folks and operators, so it’s worthy of analysis.

Is 300 BLK Effective After Penetration?

We’ll preface this with an obvious clarification: Any centerfire rifle shooting supersonic cartridges will cut through level IIIA soft body armor without much ado. But what happens once it passes through the body armor itself?

Thanks to popular gun review and testing aficionado TWANGnBANG (who you should definitely watch if you enjoy these sorts of tests), we have a definitive example of the trauma and penetration that 300 BLK is capable of, once passing through an NIJ-certified Level IIIA soft plate. A Barnes VOR-TX 125-grain JHP with polymer tip, traveling around 2,335 feet per second managed to break clean through the soft armor and penetrated around 13” of ballistic gel. Upon impact, it managed a maximum expansion of around 0.6” with a minimum expansion of .4”. Although TWANGnBANG found two of the round’s four jacket petals didn’t expand, some fragmentation did occur. This is certainly a devastating wound channel, even with just partial expansion. Mind you, this is a supersonic load.

What About Subsonic?

300 BLK 220-grainers traveling around 1,000 feet per second are pretty devastating, too. Enough so that, according to field tests of Remington’s 300 BLK loads, they can punch through bulletproof glass. If you’re a lover of pistols and other things that are subsonic, you might be scratching your head on this one. After all, bulletproof glass has been shown to repeatedly stop pistol rounds with higher grains and the same velocities.

But it’s all in the aerodynamics of the round itself. Take a big, nasty .451 Detonics Magnum with a 395-grain bullet as an example that this writer tested himself. It travels at around 1,000 feet per second, the same as Remington’s subsonic 300 Blackout. But it doesn’t get through bulletproof glass (it’s been tested, too), and that’s because it’s a wide, flat round – just like most other pistol rounds.

Dual-Purpose with a Magazine Swap

But take the long, thin, arrow-shaped 300 BLK that weighs a bit less and travels the same, and you’ll end up with a round that can be suppressed and still defeat IIIA stuff, be it soft armor or glass. That’s huge for the special operations and SWAT community – teams that have previously relied on submachine guns when they need something compact and suppressed.

If over-penetration is ever a concern, they can switch out for supersonic loads and reduce the risk of collateral damage. If the environmental concerns change and a quiet approach is needed, there is no need to change the arsenal or the gear – just swap magazines and thread the muzzle. That’s the beauty of 300 BLK in a threat-contact situation, and it’s one reason why some operators enjoy this round.