Anyone accidentally used 300 blkout in 556?

[SilentRecon]

I like 300 blkout and want one again. I like its intended use/ ballistics and makes an excellent suppressed host. I sold it because I thought it was too spendy at the time with ammo prices high, I wouldn't get the use out of it I wanted.

I almost became a victim of chambering a 300 blkout round into one of my nicest ARs. It happen to be the top round in a magazine and I looked at it for a second when I picked it up to insert it. It was a very relieving feeling. When you are speed loading mags it's easy to not really look.

Yes I label everything, extremely cautious, but somehow a single round made its way into the wrong ammo can. Ive since dwindled down to only carrying 22lr, 9mm, .45acp, 556, 7.62x39, 308 and have been wanting a 300blk again and maybe reload.

Have any of you ever come close or worse?

Here's a good article about it
https://rifleshooter.com/2019/08/ano...barrel-kaboom/

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[Marler5811]

Happened to me. It SUCKS! Someone (not me) had loaded a handful 5.56 on top of some 220 Grain 300BLK Subs in one of my magazines. I found out the hard way. Rifle was a total loss.

[SilentRecon]

Happened to me. It SUCKS! Someone (not me) had loaded a handful 5.56 on top of some 220 Grain 300BLK Subs in one of my magazines. I found out the hard way. Rifle was a total loss.

I'm sorry to hear that damn. Depending on the AR it could be multiple thousands lost but worse an injury. Glad your ok

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[Clint]

We put 5.56 once in an identically configured 6.8SPC.

The round went bang and a big swirl of blue smoke emanated from every orifice in the reciever.

Rifle and shooter were unharmed.

The bullet left the bore.

The case split across the base and ballooned the neck.

It was more like a low pressure event than an over pressure event.

[Ned Christiansen]

I did an article in one of the Guns & Ammo AR15 specials-- the 6/25/2019 edition. Yep it blowed up alright. Bullet stuck in the barrel; it got reeeaall long.

[Alpine2k3]

I got lucky with mine. I loaded magazines up before the night before I left my brother's place. I was really tired and should of known better, I was shooting rounds through my new upper and noticed the bolt wasn't all the way closed. I pulled back on the charging handle to eject the round and noticed it looked odd, I retrieved it and it was a .300 blackout round. I went through the rest of my magazines and found two more of them ended up in my other ones.

[Tokarev]

I did an article in one of the Guns & Ammo AR15 specials-- the 6/25/2019 edition. Yep it blowed up alright. Bullet stuck in the barrel; it got reeeaall long.

We intentionally chambered a 110gr 300 BLK into a S&W MP15 chambered in 223/5.56. We weighted the rifle in place and used a piece of 550 cord to pull the trigger.

The mag blew and the upper receiver bent outward at the ejection port but the bolt and carrier held together. The extractor was destroyed but nothing else "failed" inside the gun. Other than the cartridge case, that is...

The bullet ended up an inch or two past the gas block. Yes. It got really long. Probably something like 2.5" long. Pretty amazing that the damage to the rifle wasn't more significant.

One thing of note is that it took two or three chamberings to get the bolt to close on the loaded round before our little "test." Hopefully this indicates that most 300 BLK rounds with a decent crimp will not chamber without some effort on the shooter's part...

[RVTMaverick]

Hey Ned.,
I have that mag., and ofcourse read your article, great write up by the way, plus the pictures, the picture of the Super elongated .300BO with the barrel cut in half was AWESOME!

I did an article in one of the Guns & Ammo AR15 specials-- the 6/25/2019 edition. Yep it blowed up alright. Bullet stuck in the barrel; it got reeeaall long.

[WillBrink]

Happened to me. It SUCKS! Someone (not me) had loaded a handful 5.56 on top of some 220 Grain 300BLK Subs in one of my magazines. I found out the hard way. Rifle was a total loss.

Did the chamber or barrel explode? What happens?

[themonk]

I use emags for blackout and any other mags for 556.