Took a friend of mine out with a rifle I had put together for him a few years ago; he'd never fired it. It's a Spike's lower with a PSA complete upper. 16" Carbine length barrel.

He put about 100 rounds through it without any problems, it was running great.

He loaded up a mag and went to shoot it, and on the second or third round it blew up. It wasn't too spectacular, smoke out the ejection port, magazine blew out. He was fine.

The BCG was locked up, with the bolt jammed in the extension and the carrier slightly back. I popped the takedown and pivot pins and pulled the upper forward enough to remove it from the lower. We couldn't get the BCG removed at the range, and broke the charging handle trying to beat it open.

At the time, I thought maybe he had a squib and didn't notice, or had a double charged load. He had an assortment of ammo, some PMC Bronze 55gr, some Armscor 55gr, some PMC Xtac 62gr, and some Herter's steel case. The remainder of the mag that hit the ground was loaded with PMC Bronze 55gr.

At the time, I did not even consider that it could be a 300 blackout round. None of us there even own a 300 blackout, and we definitely did not have any ammo around.

So I got it home and on my workbench. Please forgive the toes and messy bench.

This is what it looked like when I got it home:

























I beat the BCG out but putting the rear lug against the bench and hitting a punch against the leading edge of the bolt carrier. Took a few good whacks but it came out without too much difficulty.

This is what I found:

















































Here's what the bolt looked like:











































Ok, so that's not great, but pretty much what I expected to find. I tried to pop the brass out with a pair of needle nose pliers, but it was stuck pretty good. So I grabbed a brass cleaning rod and went to go drive it out. Interestingly... I found a barrel obstruction less than an inch from the end of the barrel.

At this point, I figured my friend had cleared a squib without saying anything and sent another round down the barrel after it.

Surprisingly, the barrel obstruction moved pretty easily. It pushed pretty easily all the way back to the chamber area. I had to smack it a few times with a hammer to get the piece of brass out.

Here's what came out for brass:















































































So this is when I knew I was in real trouble. I went back to the upper and kept hammering the cleaning rod. After a few more hits, this is what came out.

























It's approximately 2.835" Long













And it weighs 167.1 grains













The piece of brass is 1.385" long













Here's the brass and bullet, with a piece of .223 spent brass, for scale.

























So that was exciting. I have no idea where the round of 300 came from. Like I said, none of us even own a 300 BLK. The only thing I can guess is that someone maliciously put a round of 300 BLK in a box of .223 at Cabela's, and we did not notice when loading the magazine. It appears to be a completely different head stamp than the PMC he was shooting. The head stamp that is left appears to read "00 AA Black," I'm not sure what brand of ammo that would come from.

My question is: What parts of this upper would you consider salvageable? Obviously, bare minimum I need a charging handle and extractor. I don't feel great about the bolt, either. Would you trust the carrier? What about the barrel? There is no obvious bulge, I took the handguards off and it looks completely normal.











 

Damn. Never seen a 300 AAC bullet end up like that.

 
That's kind of what I was thinking. What about the barrel? It looks fine, but I don't know how to confirm it's ok.


 

That is actually really cool.   Thanks for taking the time to post it.  Excellent PSA.

Damn..liquid metal ......another reason to roll your own

Some shitbirds put a round in the box.  I was buying a box of 7mm Mauser and found a strange round in the box 6.5mm Mauser IIRC.  

If it isn't taped up I check every round now.

Need more details...

So a 300 BLK round was in the mix in the magazine? What we are seeing is the case, jacket and core of the bullet?

IMO it looks like "R - P 300 AAC BLACKOUT" which would be Remington factory ammo.

New barrel, bolt, charging handle and check that upper really well for stress cracks.

How's your buddy? Any damage to him? I'm glad you guys are ok.

Great write up.

Also, as someone else said in another thread, always visually inspect your ammo before loading it into the magazine.

V

 
He's doing fine, just a little shook up. Pretty shitty first time out with an AR.

 
Great spot! I didn't see that earlier.

Gun control guerrilla operation... Like the hippies in the factories during 'Nam.

I wouldn't expect anything to come of it, but I would definitely contact wherever the ammo was bought. Could be a potentially fatal tampering issue.

 
Right, he was loading out of a factory box of PMC Bronze, and the first round or 2 went off fine, the third went kaboom.


What we are seeing is the case and the bullet. The bullet is still all once piece, but some of the core of the bullet was squeezed out the front of the jacket.

OK, I'm going to be the bad guy. I understand the whole wrong round in the box. I don't understand how someone who is knowledgeable would miss a .30 cal projectile on top of a casing (even of the same size) instead of .223.
A mistake that won't happen again for sure.


The story has a happy ending as no one was hurt, and a good teaching point to watch your ammo when loading.

The way I read it, OP's buddy had loaded the mag, and it was his first outing with an AR.

Wow! I'm glad your buddy is ok. Sorry about your gun.

Any idea of where the round came from?

Serious question op, can I have the projectile. I have a small collection of rounds that have been recovered from various mediums and this would look cool as hell with my others. I will gladly pp you a few bucks and cover shipping.

That's correct

 
Thanks!


I'm probably going to hold onto it, sorry. I think it's going to make a pretty cool conversation piece on my desk.

For the price of an upper, he could make his own!

It really will! If you ever get tired of looking at it PM me.

Willing to pull the trigger for me?

That's a pretty awesome visual.  I've heard of fire formed cases, I guess this is a fire formed bullet.  That's some flat out extrusion process going on there.  Thanks for sharing this.  It drives home the wisdom of checking ammo.

This was a magazine your buddy loaded right? By any chance, did he drop a round on the ground. Notice another and just picked it up thinking its the same thing?

Appreciate the thread OP, good reminder.  Since your friend wasn't hurt it was a valuable but relatively cheap lesson learned.

He'll check every round from here on out.

That thought crossed my mind as well. I've been to a few ranges where I've found un-fired rounds on the ground/grass and picked them up myself. I do however check to see if the primer is dimpled or if the bullet is set back.

Glad everyone is OK.

I would have thought the 300blk round would have failed to chamber and fire.  Thanks for correcting my misconception.

Where is the other 50 grains of bullet (assuming a 220 gr. original)? Or was this a deliberate sabotage with a 30 cal 168 gr reload in a 300 BO case?

Sheeeit.



I didn't believe the photos going around Facebook with the spaghettied bullet, but I'll be damned.

I think 2.835" of 22 caliber lead &/or copper will weigh more than 167 grains.  Looks odd to me too.

 
If I had to guess, I would say smeared along the barrel? The lead slug that came out was deformed around the cleaning rod, it could easily have lost some weight being pushed through 16" of barrel, smearing lead into the grooves of the rifling.


I figured it was a 168 factory load, but I don't see that Remington offers any; unless there is another company that uses Remington brass.

 
Nope, I don't think so. This was on private property that is pretty rarely used as a range.

OST.

Thanks OP

Here is where I get lost...

The recovered 300 BLK round is R-P 300 AAC BLACKOUT (Remington factory ammo)

Remainder of dropped mag contained PMC Bronze 55 gr


Shooter also had:


Armscor 55 gr

PMC Xtac 62 gr

Herter's steel case


Were these individual boxes of the various types or loose rounds in a container?




I'm trying to determine if the 300 BLK round came from one of the ammo boxes or if it was an accidental pick-up from the range/range gear etc.

The only thing we can come up with is that it came from one of the ammo boxes. I haven't owned a 300 in over 5 years, and never bought Rem factory ammo when I did.

 

I'm going with sabotage.

Every few months a thread pops up with pics just like yours.
CHECK YOUR AMMO.
Those suckers go bang in a big way.
Lol I also have a bullet like that in my toolbox, not mine, but it is a nice reminder.

ETA: I will say I have not seen a bullet weighing over 135 grains manage to chamber fully in this scenario. There must have been some setback or something.

Been done before

What do you mean by the last bit? Bullets under 135 can't fully seat in a 5.56 chamber? I'm new to the 300 game.

They will usually chamber in a semi auto with bullet setback.

Have you contacted the ammo manufacturer?

They might would like to know that their lots may have the wrong ammunition

He's saying longer, heavier .30 bullets won't normally seat in a 5.56 chamber because of the longer ogive, unless the bullet is forced back into the case

That's pretty awesome what happened to the bullet. Sorry about the rifle and glad your buddy is ok.

Is it possible that someone at the gun store took a 300 AAC and a 5.56 Nato out to compare them and put them back in the wrong boxes?   I see similar comparisons at the local gun store that I frequent from time to time.

That is wild. Thanks for the detailed pics.

Ah, I see.  Not quite as rare of a possibility as I had hoped.

Good to know,  thanks.  Now that I reread what he wrote that makes more sense.