R.I.P. One AR-15 Rifle – Another 300 Blackout / .223 Kaboom

I’ve read a few stories recently about someone, somewhere, shoving a 300 AAC Blackout cartridge into a .223 / 5.56mm rifle and pulling the trigger – subsequently blowing their gun to bits. Some folks call BS and say it can’t happen as the rifle won’t go into battery and fire.

Well, I’m a believer now, considering a guy 3 lanes down from me blew up his fairly nice looking AR today. In the confusion, I was not able to get the brand of the rifle, but that matters little. Containing 55,000 pounds per square inch of pressure is not in the job description.

This was the round below the cartridge bomb in the magazine. I found it on the ground amongst lotsa small pieces of magazine, spring and follower – and quite a few case fragments. As you can see, it absorbed some serious violence.

I was pretty occupied with my own business, gleefully trying out two new SilencerCo silencers for which I’ve waited about 10 months. A 22 Sparrow SS and an Octane 45 by the way. And yes, they’re awesome. Happiness = That feeling when your slide cycling makes more noise than the gun shot. That nirvana was achieved with a Smith & Wesson M&P22 with a SilencerCo Sparrow using Aguila Subsonic 60 grain .22LR ammunition.

Suddenly I heard a “splosion” noise and a scream from a few lanes to my right. Running over to see what happened, I saw a man holding his hand and obviously somewhat shaken up. I immediately started looking at his face as he was somewhat disoriented and all was clear there. His left (support) hand looked like he had fondled a few bricks of charcoal for a while. Thankfully, and maybe miraculously, no cuts or blood anywhere. While his hand was “stinging like crazy” in his words, there did not appear to be any burns of consequence. This is one incredibly lucky guy, especially since I can’t be sure he was wearing shooting glasses. The way they were placed on the table, I’m not sure he had them on when he blew up the rifle.

Here’s the apparent sequence of events, picked up from listening to the rifle owner and the shooter.

The owner had two uppers at the range. A .223 and a 300 AAC Blackout. He obviously hand loads as there were 100 round ammo boxes of each type nearby.

The shooter appeared to be new and somewhat inexperienced. I can’t be sure, that’s just an observation from seeing the interaction after the kaboom. Either the shooter picked up a magazine full of 300 Blackout cartridges, or the rifle owner handed him a magazine loaded with Blackouts. I can’t be sure. They weren’t sure themselves.

The shooter loaded the magazine of 300 Blackouts in the .223, chambered a round, and fired. Then the Kaboom. I was not able to discern, nor was the owner, whether the shooter felt anything abnormal trying to chamber the first round. As  the shooter appeared to be inexperienced, I’m not sure they will ever sort that out.

Once we determined the shooter was physically OK, I wanted to get out of their business, so I didn’t get any photos of the rifle, but I can describe the damage. In short, it was pretty much totaled. Perhaps the Magpul front hand guard, rear stock and trigger group can be salvaged. That’s about it.

Here’s a .223 Remington cartridge dropped into a 5.56mm chamber.

The magazine blew up, along with spring and follower. And you can see what happened to the other rounds in the picture here. I *believe* the fact that he was using a polymer magazine may have saved the shooter from additional injury. The explosion clearly took the path of least resistance. Perhaps a metal magazine would have allowed more pressure to go in other directions in addition to out the magazine well.

The magazine well on the lower was bulged out. Kind of like an Elmer Fudd cartoon shotgun.

The upper receiver was also bulged out from the explosion.

The bolt and carrier were both trashed – bent all to hell and completely stuck in the upper and barrel extension.

I assume the barrel extension and barrel were trashed, but as everything was fused together, there was no way to tell for sure until they rip things apart. Shoving a .308 inch diameter bullet into a .223 inch hole is asking for damage I would think.

While I was not shocked at the damage to the aluminum upper and lower, I was surprised at how much the bolt carrier and bolt were trashed. That’s hard stuff there.

Here’s a 125 grain 300 Blackout cartridge dropped into the same 5.56mm chamber. Too close for comfort?

With the brief opportunity I had to look, that’s about all I could tell. But now I was curious. Would similar rounds allow the .223 rifle to go into battery? I decided to try under much safer conditions.

After removing the bolt and carrier from my Smith & Wesson M&P 15 VTAC (5.56 chamber) I dropped in a .223 Remington round to get a rough visual on where it sat. OK, that worked fine, as expected. Next, I dropped a variety of 300 AAC Blackout loads into the chamber, exerting no pressure at all and just letting the round fall. As expected, the big subsonic rounds didn’t get close to proper depth, however some of the longer and skinnier bullet profiles did – mainly the 110 and 125 grain ballistic tip bullet types. Not to the full and proper depth, but close. Close enough where a little encouragement by an inexperienced shooter could force the bolt into battery.

Lessons?

Wear eye protection. Always. This guy won the lucky human award today and I don’t think that’s given out more than once per lifetime.

When bringing a new shooter to the range, hover over them like a helicopter parent. At least until they gain some knowledge and proficiency.

If you own both rifles, figure out your own method for segregation. Perhaps wrap the Blackout magazines with colored tape, or put a colored base plate on them so they’re easily visible.

It might not be a terrible idea to take one or the other rifles to the range, but not both on the same visit.

Whattdya think?

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