AR15 Malfunction

[Nicr1991]

Ok guys,

Need some help identifying the cause of a malfunction.

So I was taking out a brand new AR15 today and getting it sighted in. I loaded up the mag 30rds, pulled the trigger, bang, and then nothing. The bolt looked like it was about 90% closed so I tried racking it to clear the malfunction, and the charging handle was stuck. Like neither I or the Range Officer could get it back. When we disconnected the upper and lower the bolt and charging handle were still stuck. There was a round in the chamber but it's like it couldn't feed all the way or something. Finally we were able to clear it, but we needed a screw driver to pry the bolt back while pulling the charging handle. Fired the rest of the magazine fine, but then when I loaded a new magazine the exact same thing happened with a fully loaded magazine. First round shot fine then it jammed on the second...


Anyone have any ideas about what could have been the problem? And how to prevent it from happening in the future?? Thanks!!

 

[halfmileharry]

Ammo? Mags? Brand of gun?
Lubricated properly?
I'm guessing I'd check the mags and load them one round light.

 

[deo62]

Seen that happen to a guy running a DPMS. He was using some cheap reload ammo. Had to hammer on the charging handle to remove everything. Replaced charging handle and inspected, couldn't find anything. He switched ammo and never had the problem again.

 

[mammynun]

Remove mag. Collapse stock (very important) and slam butt stock on the ground.

I didn't watch this video cause I'm on my phone, if it sucks Google "AR mortar" and you'll get more info.

https://youtu.be/kzBdyubc0Uk

 

[NyleRN]

Ammo? Mags? Brand of gun?
Lubricated properly?
I'm guessing I'd check the mags and load them one round light.

This^^^ When you say "new" do you mean factory built or built by individual? May need to scrub the chamber real good with bore cleaner. Might put a go/no go gauge to it

 

[NyleRN]

Remove mag. Collapse stock (very important) and slam butt stock on the ground.

I didn't watch this video cause I'm on my phone, if it sucks Google "AR mortar" and you'll get more info.

https://youtu.be/kzBdyubc0Uk

Flip the safety on too.

 

[mammynun]

Flip the safety on too.

If possible, yes. I should have put that on there.

 

[Nicr1991]

Ammo was Midwest ammunition from Point Blank in greenwood. Mag was just a steel mag. Matching Bushmaster upper and lower. My buddy built it for me. He's built tons of em and they all shoot fine. I probably won't be slamming my stock on the ground. Don't wanna shatter it.

 

[NyleRN]

What about the barrel? I guess I'm still not getting a clear picture. Was it a factory built upper and he just snapped it on the lower? Have you taken the upper off and removed CH and BCG and dropped a round in the chamber? Does it seat all the way with just gravity?

 

[halfmileharry]

Try some different ammo. I'm not bad mouthing Midwest but you won't be the first or last to have some issues with the stuff.
ONLY one mag tried? Try a different mag as well. Make sure the bolt is well lubed.
Just because your buddy has had good luck on previous builds it doesn't mean something didn't work right.
Start with the basics and ONLY ONE fix at a time so you know where your problem lays.
Good luck with it and please let us know what makes the rifle run properly.

 

[POB]

Gotta be the ammo.

 

[Nicr1991]

Thanks, I'll definitely keep you guys posted. My gut reaction is the mag because it only happened after the first round with a fully loaded mag.

 

[M67]

Remove mag. Collapse stock (very important) and slam butt stock on the ground.

I didn't watch this video cause I'm on my phone, if it sucks Google "AR mortar" and you'll get more info.

https://youtu.be/kzBdyubc0Uk

Ammo was Midwest ammunition from Point Blank in greenwood. Mag was just a steel mag. Matching Bushmaster upper and lower. My buddy built it for me. He's built tons of em and they all shoot fine. I probably won't be slamming my stock on the ground. Don't wanna shatter it.

You won't shatter the stock, but sling shotting gives you the most leverage to clear a stuck live round. Safety on, stock collapsed, and give it a good thump. If it does shatter, replace the sloppy one on it and get a Magpul MOE or SLK

The round in question could have just been out of spec, did you load it back into the magazine and try to rechamber it?

 

[sig1473]

Bushmasters are also known to have out-of-spec chambers amongst other problems.

 

[halfmileharry]

Thanks, I'll definitely keep you guys posted. My gut reaction is the mag because it only happened after the first round with a fully loaded mag.

I'll be in Southport until around 5:00pm today if you need to borrow known working mags.
I can check out fit and bcg/ch handle function for you.
ARs are a simple creature and sometimes you just need a different approach.

EDIT:
Sometimes on builds you can get parts on the opposite edges of tolerances that can give you grief.

 

[Leo]

Bushmasters are also known to have out-of-spec chambers amongst other problems.

That is the first time I heard of that. The only ones I have ever had come back were when people put crap ammo in Bushmaster CMP models that have a slightly tighter ( but still within SAAMI spec) target chambers. Plain jane Remington, Winchester, PMC, etc ammo worked fine in them, but clearly bozojoe reloads were a problem.

 

[Leo]

For the OP, yes, magazines can be defective, but they will not jam a round in the chamber. Even a slightly dented round will either chamber or be able to be extracted with the charging handle.

I would buy a box of new ammo, Federal Gold Medal match is not required, but some factory Remington, Winchester, or Lake City will be fine. Good Luck

 

[GIJEW]

This could be a head-spacing vs case resizing problem. Say, the case is neck-resized or the shoulder dimensions are less than fully reset and the variances on the head-spacing are a little tight, you could get problems with a stuck case.

 

[DoggyDaddy]

For the OP, yes, magazines can be defective, but they will not jam a round in the chamber. Even a slightly dented round will either chamber or be able to be extracted with the charging handle.

I would buy a box of new ammo, Federal Gold Medal match is not required, but some factory Remington, Winchester, or Lake City will be fine. Good Luck

This could be a head-spacing vs case resizing problem. Say, the case is neck-resized or the shoulder dimensions are less than fully reset and the variances on the head-spacing are a little tight, you could get problems with a stuck case.

If it were an ammo problem though, why would it only be happening on the second round of a full mag? I thought the OP said that the rest of the mag ran fine? Seems like if it were ammo, he would be having problems intermittently throughout the mags.

 

[Jeremy1066]