300 blackout in a 223 kaboom. (Pics inside)

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One of the oddest I have seen was when a couple of the guys I knew were going on an elk hunt and one had only ever shot pistols and was going to borrow one of the others rifle for the hunt. So they were at the range letting him try out various rifles to pick from. He was doing alright until he ran a few rounds out of a 300 Weatherby mag and couldn’t even hit paper. Turns out 256 win mag shoots horribly out of a .300.

I wish I had grabbed a case back then as it looked quite different. Looked like you cut the neck off and blew flutes into the shoulder, when the short case formed to the longer chamber. That one didn’t hurt the rifle though.

Never fun to play the shell game with firearms.
 
Wow. Note to self: Arisaka==>Bullet Swaging Machine. AR15==>Not so much.
 
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The lower did well. I had a Bushmaster that I shot that had a case head separation. The side of the lower blew out. It was totally destroyed. I still have a small piece of the aluminum in my thumb
 
Crazy to see that tool steel bolt get peeled apart like a Snickers bar wrapper while the much-derided polymer lower held together.
 
Glad you both were okay. Thanks for sharing.
I wonder how it would differ with a subsonic round. Not that I'm will to test it out. But I would think half the pressure would be of lesser damage.
I better dedicate some mags for the BO.
 
My Grandfather used to say, "Check, check and check once more." It goes for making sure your caliber is correct when you're loading a gun, and for "unloaded" guns as well:

He preached that after one of my cousins insisted that a .257 Roberts rifle he was using was unloaded and didn't want to cycle the action again before climbing into the truck and putting the rifle in the gun rack. Grandfather suspected he was one short, and after the cousin kept insisting it was clear he had the cousin point the gun towards a large oak tree about 15 feet away and pull the trigger. Sure enough, it went BOOM! and blew a chunk of bark off the tree trunk. Needless to say the cousin was near to crapping his pants, while my Grandfather just climbed in the truck...lesson learned.

Glad you guys are OK..sadly for your friend, "an expensive lesson learned."

Stay safe!
 
:what::what::what:

This is a seriously scary mishap...

I think your friend is lucky to not have been injured.

This highlights the reason why I won't neck size .308 brass to reload for my 7mm-08. In the big scheme of things, buying brass marked correctly is inexpensive compared to the cost of a wrong ammo mishap.

You seem to be taking it in stride... I think I would have gone ballistic.
 
I wonder what it looks like with a regular upper and lower? Kinda curious what would be salvageable.


I load all my 300’s in steel mags. 223 in Pmags. It doesn’t really help with anyone else but it keeps me straight. You can tell them apart in the dark easy too unlike color coding stuff.
 
This highlights the reason why I won't neck size .308 brass to reload for my 7mm-08. In the big scheme of things, buying brass marked correctly is inexpensive compared to the cost of a wrong ammo mishap.
While I understand this sentiment, I don't think the risk is quite the same. A .308 won't chamber in a 7mm-08, and a 7mm-08 chambered in a .308 won't cause dangerous pressure. I can't get brass head stamped "243 Ackley" so all of that brass is fire-formed .243 Winchester. The latter is safe to shoot in a .243 Ackley rifle, and the former won't still chamber in a .243 Win.

What I've learned in this thread is that a .300 BLK WILL chamber in a .223/5.56, and that IS scary.
 
Good to hear that both of y'all were ok.
I posted about a blown up AR back in May.
https://www.thehighroad.org/index.p...300-blk-in-your-5-56-ar.836440/#post-10829573

One reason I have avoided the 300 Blackout is that it will chamber in a 5.56. I went with the .277 Wolverine for two reasons. One is that it will not chamber in a 5.56 and the other is that it out preforms the 300.
I also only use OD Green Hex Mags in my .277.
 
Beenbag,

Is your friend going to pay to replace it? Or did he at least offer to do so?


It was his gun, he had just brought it over for me to change the FCG for him, which happens to be one of the few things I salvaged. He is, however, rebuilding the gun. Or I should say, I am building him a new one with SOME of his old parts. He went with some upgrades and mods he wanted to do anyways.
 
It was his gun, he had just brought it over for me to change the FCG for him, which happens to be one of the few things I salvaged. He is, however, rebuilding the gun. Or I should say, I am building him a new one with SOME of his old parts. He went with some upgrades and mods he wanted to do anyways.

Oh ok
I really hope he learned that you don’t pick up other people’s stuff and don’t double or triple check the contents.
 
Oh ok
I really hope he learned that you don’t pick up other people’s stuff and don’t double or triple check the contents.

He’s a good guy, just not an informed “gun guy”. He may have thought, “well he’s got cases of ammo and stacks of loaded mags, I’ll just shoot his and save my 17 rounds that I own”, I don’t know for sure, but if that’s the case, it was a costly one. And I’d hope he’d know I’d have given him ammo if he needed it to check function but again, who knows.
 
Thanks for not posting the damaged Fruit of the Loom pictures.

I was behind him so I didn’t see the initial kaboom, and honestly, he didn’t know what happened until I evaluated and seen the mag of 300 blk laying on the table. His exact words, “I thought we didn’t get that back pin pushed in all the way because it kinda raised up in the back”.
 
The .300 Blackout fills not one single performance envelope that interests me. I’m unimpressed with a weak sauce .30 caliber carbine round, and don’t care one bit about how well it performs when suppressed. Full power rounds also suppress more than satisfactorily enough to be hearing safe and not spook game. So why bother with shooting a .30 caliber bullet with a rainbow trajectory?

Now that I know a loaded .300 Blackout will chamber and get a false headspace in a 5.56mm chamber it not only fills no need, but is also a potential hazard.
 
This thread is more about safety concerns when not verifying what ammunition is in the magazine.
It's not a thread to bash a particular cartridge.
 
Is it not a safety concern when a poorly designed wildcat cartridge specifically made to share a platform with the parent cartridge will chamber and false headspace on the projectile in a chamber cut for the parent cartridge of different caliber? Particularly considering that the same magazines are utilized and can easily be mixed up introducing this poorly designed cartridge into a chamber not designed for it.

I call that a problem, and one that is fairly caliber specific here due to two cartridges sharing detachable magazines for the same model(s) of weapon.

This issue could have been avoided if more diligence had been paid to the cartridge design and loaded round dimensions.
 
While I understand this sentiment, I don't think the risk is quite the same. A .308 won't chamber in a 7mm-08, and a 7mm-08 chambered in a .308 won't cause dangerous pressure. I can't get brass head stamped "243 Ackley" so all of that brass is fire-formed .243 Winchester. The latter is safe to shoot in a .243 Ackley rifle, and the former won't still chamber in a .243 Win.

What I've learned in this thread is that a .300 BLK WILL chamber in a .223/5.56, and that IS scary.

I do the same, form .260 and 6mm SLR from .243 Brass, neither will fit in a .243W chamber. A .243 round won't fit in a 6mm SLR and if a .243 does finds it's way into a .260 it will just fire-form the brass while the .243 bullet rattles it's way down the barrel.

The .300 AAC is a different matter and does require some due diligence in handling, marking and storing.
 
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