I know there are different "classes" of malfunctions, but I don't know how to properly categorize within that structure, or name this particular failure, so, I'll describe it as best I can, and let you be the judge.

This happened to my friend while zeroing a new optic. Good rifle (factory BCM) and good ammo (unsure of exact make, but factory-manufactured brass-cased ammo). Unfortunately, because most folks try and perform some type of immediate action upon realizing a malfunction, the situation could not observed in it's most immediate nature. After immediate action proved unfruitful, we realized he has a brass-over-bolt issue; specifically an unfired, mangled round jammed up above his gas tube (facing forward). Had to separate the receivers to remove the round, as there was no way to get enough leverage on the round to remove it through the ejection port or mag well, with the tool we had (Gerber multitool). So, certainly a catastrophic failure that would have been bad news in a real-life situation. My best guess as to a cause is a magazine issue of some kind; a round not being properly presented to the bolt face and/or chamber. Or the lips letting a round loose before the bolt actually came back forward to strip one. What do y'all think?

A little more background: He had already shot at least ninety rounds without issue that same day, and has shot the rifle plenty before that. He was using a silencer and a Gemtech adjustable carrier, which he has also employed previously without issue.

I think there’s just as much chance it’s an ammo problem or issue? I’d want to know more about the ammo.

If it was a fair chance an ammo problem, I’d disassemble, clean, lube, then try other rounds. While in there look to see there’s no obvious damage.

Just saying, even with factory ammo, some guns don’t preform well, with certain ammo. Yes, the magazine could be a player too.

Jerry Miculek did a YouTube video about a year ago titled “The Dreaded Death Jam” that I believe addresses this type of malfunction. Jerry states it’s normally caused by a bad magazine, the feed lips to be exact.

quote:

Originally posted by Badhammer:
it’s normally caused by a bad magazine, the feed lips to be exact.

Yup.

It starts as a problem with the feeding* process, and because feeding is what the magazine does, if the cartridge is released too soon or at a bad angle it can end up in the bolt override position in the receiver. It could conceivably be due to a badly deformed cartridge that’s not fed properly by the magazine, but it’s more likely due to a defective magazine. Problems can also occur with the gun’s functioning, but I’ve never seen that result in the bolt override.

* Pushing the cartridge into the chamber after the cartridge is pushed up to the top of the magazine is … yes, chambering.

And as discovered, it can be very difficult to clear. That is one reason for having a backup handgun in addition to the rifle.

What type and brand of magazine was being used at the time?

Sorry I omitted that. Pmag. Unsure of gen.

quote:

Originally posted by KSGM:
Sorry I omitted that. Pmag. Unsure of gen.

That could be your problem right there. Most people don't get to the point where the PMAG's feed lips have worn down to where they cause malfunctions...but this does happen.

And as much as Magpul QC is pretty on point...everybody makes mistakes.

Mark that magazine and use other mags and see if the problem recurs.

Well, all of you confirmed my suspicion. Hopefully he remembers which mag it was.

Also, if ammo is stored long-term in pmags without the top cover on, this can happen.

quote:

Originally posted by PGT:
Also, if ammo is stored long-term in pmags without the top cover on, this can happen.

I did consider this might tie into that other recent thread. I don't know how long he had the mag loaded up. If I had to guess, I'd say it wasn't a long-term loaded mag. Either way though, it's a mag thing.

Hard to get the beans over the frank but it can happen when the pmag lips wear out as stated. That mag should be relegated to training obviously. In the future, he can hold the bolt back with a finger or pen or something and karate chop the charging handle forward. Done properly this typically dislodges it without too much of a fuss.

I have seen one where the bullet got magically attached to the charging handle and we couldn't dislodge this way and yes, rifle surgery was required.

quote:

Originally posted by Anubismp:
In the future, he can hold the bolt back with a finger or pen or something and karate chop the charging handle forward. Done properly this typically dislodges it without too much of a fuss.

I have done that plenty of times myself, but it wasn't happening in this particular instance. This was an atypical brass over bolt, in that something happened, the shooter performed immediate action, and a live round got lodged above the gas tube, in FRONT of the charging handle.

I am actually talking with the guy as I type this, and we are better recalling the specific details. Still a mag thing, I reckon, but a bit different than I perhaps originally presented. I apologize for any confusion.

In talking with him, I may have deduced the sequence of events. Firing the rifle, gets a click, performs immediate action, no spent case ejected, charging handle doesn't go all the way back forward, realizes problem, round is stuck as previously described.

So either an underpowered round didn't get a full stroke to pick up another round, or the bolt outran the mag. Either way, when he charged the gun, it seems the mag did him dirty in it's delivery off that next round.

The biggest flaw in the design, that there’s room enough above the bolt for that to happen. I’ve seen it literally take three men and a pair of pliers to clear that jam with the upper off the rifle. The round finally came out with about a 65° bend in it.


There are ways they could’ve designed it to not have that design problem, but it would’ve complicated things a bit manufacturing and assembly wise.