Double Feed

[Detective_D]

What causes them? Me and the wife shot this past weekend and this happened once. First time it ever happened.

My wife loaded the Mag, so I dont know for sure that she didnt mess up something with that. It happened while she was shooting. It tried to load two live rounds at once. One on top of the other. I should have taken a picture of it. Both rounds had the tips attempting to enter the barrel.

This is the first malfunction at all with this gun. It is an LMT complete with LMT bcg and sopmod with H buffer. We were using the Hornady TAP practice steel case ammo.

I really dont think it is an ammo related failure. I just need to know what would cause a double feed.

Thanks in advance.
~D

[Failure2Stop]

When 2 live rounds are simultaneously fed/fail to chamber you have 2 possible problems-
1- Magazine.
2- User error.

In my experience the most common cause is the user "slapping" the magazine during the load when the bolt is held to the rear. This causes the stack to drop and spring up, frequently allowing one or more rounds to jump free. When the bolt is released, it still tries to feed a round from the magazine and move it toward the chamber, but the second round interferes.

It can also be caused by a partial chambering, followed by retraction of the Ch by the user, followed by a second feed/chamber fail.

A bad magazine can also be the cause, but I have not seen a mag related double feed in about 8 years (when we learned to diagnose bad mags and return them). This is not to say that they do not happen, just that they SHOULDN'T, if you do your job .

There are other types of "double feeds", but they involve fired cases, and are a different diagnostic path.

[markm]

It's likely a mag or ammo problem. Could be a fluke.

Either there was some issue with the round that fired prior to the malf that sent the bolt group back in an unnormal fashion (too fast/too slow), or the mag goofed up.

[carbinero]

Just tested a new CMMG 16" LW middy and had this problem with 2 old mags, (neither of which had a problem with 2 other ARs.) On each mag, first 2 rounds went bang, the #3 and 4 rounds fought for who's next. However, zero problems with 6 p-mags...so there's my solution.

[Detective_D]

This was done in a practically brand new pmag. I have used this mag maybe 5 times so far and no other problems.

I am curious about something though demigod, if you dont mind me asking, how could this be caused by ammo if it was a double feed of two live rounds? I could understand if it was one fired and one live double feed, but this one kinda stumps me.

I am really thinking that she must have done something wrong when she loaded them up. I dont really know what, but I will have to watch her load up next time. This was her first time to load one though.

Thanks for the replies guys.

[Failure2Stop]

If it happened during a string of fire- not the first round- I would be suspicious of the magazine. I would mark the mag with a big red frowny-face and relegate it to training use only.

PMags are great, but don't get married to your mags. If it has another double-feed, dump it. Just like Ol Yeller, as long as they are good, sing their praises, but as soon as they get rabies, you gotta shoot 'em in the head.

[markm]

I am curious about something though demigod, if you dont mind me asking, how could this be caused by ammo if it was a double feed of two live rounds? I could understand if it was one fired and one live double feed, but this one kinda stumps me.

If the last round fired cycled the bolt unusually slow or fast, it may have upset the feeding of the subsequent round. The last round could have had a goofy powder charge or bad headspace/case dimensions that gave it a whacky extraction.

On the other hand, sometimes, you have to chalk up an occasional malf on the AR platform to a Fluke and move one.

[Detective_D]

10-
Thanks for the explanation.

I will definitely mark the mag as I know which one it was and see if it happens again.

Thanks for your help guys.
~D