300 blackout in a 223 kaboom. (Pics inside)

[someguy2800]

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.

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.

Have you ever shot a 300 blackout?

 

[Coal Dragger]

Yes I’ve shot one.

Nothing about it was remotely impressive to me.

 

[adcoch1]

If you are loading subsonic loads with fat bullets it won't chamber. And i believe the barnes 110 grn bullet load won't false headspace either. So it isn't necessary to berate the cartridge as being poorly designed. It IS a very good reminder to PAY ATTENTION while shooting and not put the wrong ammo in the wrong gun!

 

[Englishmn]

Load them like this no problem.

Still better to always check.

 

[Englishmn]

Found this in a story about 300blk blowing up a 223.

Almost made it.

 

[rbernie]

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.

This is an issue that has been around as long as there have been cartridge-based firearms - so much so that SAAMI has been producing a safety publication on this topic for many, many years:

https://saami.org/wp-content/upload...Site-and-Brochure-Master-Revised-5-7-2018.pdf

To characterize this as as 300AAC issue seems a bit hyperbolic.

 

[hdwhit]

Glad to hear there were no serious injuries.

Some time ago, I got a bunch of 223 brass where the necks were all mangled. Looked like it was ripe for conversion to 300 BLK, but that potential artificial headspace problem has kept me from ordering a 300 BLK upper. I can see myself getting distracted, ruining a rifle and getting hurt for no good purpose.

 

[jr_roosa]

Pretty sure none of my go-to 300blk loads will chamber unless the bolt has enough momentum to push the bullets into the case.

I've never tried to get them to chamber by force.

-J.

 

[Englishmn]

Pretty sure none of my go-to 300blk loads will chamber unless the bolt has enough momentum to push the bullets into the case.

I've never tried to get them to chamber by force.

-J.

That's what the forward assist is for.

None of my loads will chamber either it seems like the lightweight supersonics are only ones that fit.

 

[d'zaster]

That is a serious reminder to always double check. Thanks OP.

 

[Zaydok Allen]

So you were helping this guy by working on his gun, and then he thought it would be ok to pocket one of your magazines and shoot your ammo without asking?

That's instant karma right there.

And now you are going to help him build a new gun? You are seriously a way nicer guy than I am. I'd have no problem donating a little ammo to a friend if they asked.............. but just taking it? Maybe you're just setting up a karma payment plan for this guy. Eventually he'll owe you his car.

That is seriously a scary deal, and I had no idea 300 BO would falsely headspace and chamber in a 223. I don't shoot 223 or own an AR any more, so it never even occurred to me. Glad no one was hurt, and this is a good safety reminder. Thanks for sharing.