• Winner! Quick Shot Challenge: Caption This Sniper Fail Meme

    View thread

What to see what happens when you fire a 300 Blackout in a 5.56?

RHunter

Sergeant
Banned !
Full Member
Sep 2, 2013
857
8
Florida
You get a fire-formed .223 bullet

300-aac-blackout-5.56-rifle.jpg
 
The long sub's generally WONT fit in the chamber.

The short supers generally WILL fit in the chamber.

Im surprised in the first pic of the cut apart barrel the thing didnt blow like the second set of pictures. Looks like a bolt gun barrel in the first pics.
 
I did not do the cutting, a friend sent me the photo. I would have just tossed it in the trash if I did it and not told a soul. :) After that Ka boom down the road from my place with that 338.. I'd never fess up to doing something this stupid. That poor guy became a celebrity of stupid over that.

I don't know what gun that photo came from but you can see the two rings from the set screws of the gas block. The threads on the chamber end are confusing. I am thinking that barrel began its life as something else.

I just thought it was pretty cool how it squeezed that .30 cal bullet that far down the pipe.

It is pretty amazing the destructive force of 18 grains of h110 or what ever blew that AR bolt apart.
 
Shit I had to go look at SAAMI prints. I never realized it would even come close to chambering until 30 seconds ago. Then again I dont own nor have I shot a 300 Blackout. Hope nobody got hurt but that is a pretty cool picture.
 
I just thought it was pretty cool how it squeezed that .30 cal bullet that far down the pipe.
It is pretty amazing the destructive force of 18 grains of h110 or what ever blew that AR bolt apart.

There are bullet swaging dies that can reduced the diameter of a bullet, but that is generally lead.
I wonder how many tons of pressure you would need to do this one. Would a 12 ton or 20 ton have enough force?
 
Oh just dont go over to 300blktalk and suggest to those guys they actually LOOK at the fucking ammo before slamming mags into guns.

They "use different colored mags" or "I only use 20 rd mags for 300blk and 30's for 5.56" or "I use these wrist band things I wrap around the mags" or "I will only use brass that has a real 300BLK headstamp" or "insert other fucking dumb idea here".

God forbid you suggest "hey dumb ass, why not inspect your ammo before putting it in a gun" you get shit on for not being on board with their dumb ass idea. The biggest horn blower over there that used some gimmick to "attempt" to not shoot 300blk in a 5.56 gun DID IT. Guess what, his crutch didnt work.

Dont get me wrong, I am very active over there and there is a TON of good info, but it seems that people would rather use a crutch(that obviously doesnt work in some cases) vs. looking at what they feed into their guns.
 
Great visual of why you need to be extra careful if you run both 556 and 300 Blk Out ARs. One of the major selling points of the 300 Blk Out is that all it take is a barrel swap... all the other parts are the same. So I can see how if magazines are not clearly marked or all gear separated by caliber a split second of carelessness can cause a potential big problem.

There's a margin of safety in that a 300 Blk Out round doesn't "easily" chamber completely (bolt closed ready to fire). I haven't tried it in my rifles but I believe the bullet has to be pushed back into the case to allow the 300 Blk Out case in far enough for the bolt to close in a 556 barrel. So I think it comes down to neck tension/crimp that makes the difference between cambering completely or not. There was a post on another forum that showed how it was possible even with some of the heavier bullets.

So I guess the moral of the story is to be careful.
 
Oh just dont go over to 300blktalk and suggest to those guys they actually LOOK at the fucking ammo before slamming mags into guns.

They "use different colored mags" or "I only use 20 rd mags for 300blk and 30's for 5.56" or "I use these wrist band things I wrap around the mags" or "I will only use brass that has a real 300BLK headstamp" or "insert other fucking dumb idea here".

God forbid you suggest "hey dumb ass, why not inspect your ammo before putting it in a gun" you get shit on for not being on board with their dumb ass idea. The biggest horn blower over there that used some gimmick to "attempt" to not shoot 300blk in a 5.56 gun DID IT. Guess what, his crutch didnt work.

Dont get me wrong, I am very active over there and there is a TON of good info, but it seems that people would rather use a crutch(that obviously doesnt work in some cases) vs. looking at what they feed into their guns.

They really can't tell the difference between a 30 cal and a 22 cal bullet just by looking? Do they have 300blackout mixed in with 223 just for fun or they to busy playing commando? 99% of the time I only have 1 caliber of ammo out at a time while shooting. Also 99% of the time I can identify the caliber just by the spent brass on the ground, sometimes 1/2 covered in dirt. I have seen and identified before bending over and picking up, 22lr, 9mm, 40sw, 45 acp, 357 mag, 44mag, 223/556, 762x39, 762x54r, 308, 30-06, 300wsm, 30 carbine, 50Bmg, probably a few others.
 
Oh just dont go over to 300blktalk and suggest to those guys they actually LOOK at the fucking ammo before slamming mags into guns.

They "use different colored mags" or "I only use 20 rd mags for 300blk and 30's for 5.56" or "I use these wrist band things I wrap around the mags" or "I will only use brass that has a real 300BLK headstamp" or "insert other fucking dumb idea here".

God forbid you suggest "hey dumb ass, why not inspect your ammo before putting it in a gun" you get shit on for not being on board with their dumb ass idea. The biggest horn blower over there that used some gimmick to "attempt" to not shoot 300blk in a 5.56 gun DID IT. Guess what, his crutch didnt work.

Dont get me wrong, I am very active over there and there is a TON of good info, but it seems that people would rather use a crutch(that obviously doesnt work in some cases) vs. looking at what they feed into their guns.


Ok - my prior post "be careful" message was too watered down. This hits it on the head. If you confirm the rifle and ammo match you won't have a problem.
 
I color code magazines as a safety measure. I've considered using other means but it still boils down to being responsible, safe, and having situational awareness when firing a weapon. Hopefully nobody got hurt, it is a pretty amazing picture!

Sent from my SCH-I545 using Tapatalk
 
My 300BLK magazines are black STANAG mags and my 556 mags are FDE PMags, not only can I see the difference I can feel the difference even with gloves on. The biggest thing is I dont EVER carry the two on the same magazine carrier because under stress when muscle memory and tunnel vision kick in you won't notice color or a slight difference in contour and a few ridges (PMag).