My problem child AR. WTF???

[F-Trooper05]

So I've had this gun since about March and I've had one issue after another with it. First I had a pinned and welded FH that was loose and had to go back to get re-done. Then I had a BCG that was failing to eject. Got a new BCG and it's worked great for well over 1k rounds.

Well yesterday I was shooting and I had two malfunctions that I don't understand.

1) Three double feeds with three separate mags (two USGI's with a green and brown follower, and one Gen2 pmag. All happened back-to-back. Couldn't possibly be all three mags were bad, could it?

2) I had at least five failures to feeds. So I put a single round in the chamber with an empty mag about 10 times, and the bolt wasn't locking back at least half the time. I'm using an H2 buffer on a 14.5 middy, which I'm assuming is the issue, but why the hell would it work fine for 1k rounds and just now start acting up?

I'm running Fed M855 which is literally all I shoot, so I'm having a hard time believing it's the ammo.

Gun is a 14.5 BCM middy, Centurian Arms BCG, H2 Buffer, and complete Colt lower.

Any thoughts? More than anything I'm curious why this would just now be happening after 1k trouble free rounds?

[JimmyB62]

Have you re-lubed it after those 1k trouble free rounds? H2 on a 14.5 middy may run when clean and wet but it's still marginal.

Also, were the double feeds actually two live rounds from the mag, or a failure to extract with a live round trying to feed?

[VIP3R 237]

I don't know why it started acting up but bcm recommends an H or even carbine buffer for the 14.5 middys. Id start there.

[MistWolf]

Are you sure it's a double feed your getting? A double feed is when two live rounds are stripped from the magazine. This is a magazine problem.

If you are getting a getting an empty case and a live round caught in the action, that's a Failure to Eject and it is not a magazine problem. From the rest of your description, my guess is your rifle is Short Stroking

[Onyx Z]

The 1k rounds that worked great were probably from a different lot of powder and loaded slightly hotter to achieve the same velocity. The gun was running on the verge of not running.

I'd say it's short stroking. Drop to a H or Carbine buffer and it should fix it.

[SpeedRacer]

The gun was running on the verge of not running.

I'd say it's short stroking. Drop to a H or Carbine buffer and it should fix it.

This would be my guess. With the H2 buffer it was on the ragged edge and probably got a little dirty/dry. I bet an H buffer and good clean/relube would get it back on track.

[Hmac]

I had this happen on my 11.5 SBR with H2 that had over 5000 trouble-free rounds...thought I was getting double feeds. Turned out to be all-of-a-sudden short stroking. I ultimately fixed it by replacing the gas tube. The point being...you might consider short stroking due to a problem with the gas system....obstructed port, loose gas key, leaking gas block, misaligned gas tube.

[F-Trooper05]

Definitely true double feeds (I know the difference). And I'm aware that double feeds are almost AlWAYS magazine related, which is why this one baffles me.

As for the short stroking, obviously switching to an H buffer is the first step, which is no big deal. I'm just curious why now all of a sudden this would be necessary? I shoot 3 to 5 times a week, and suddenly (less than 24 hours after my last shoot) it goes tits up without any changes to the weapon system?

[Wake27]

I had a similar situation with my Noveske. Had been running great for about 3k rounds than I started having all kinds of problems. Turns out one of the gas rings broke but what made it interesting (before finding the cause) was that after several back to back failures, we put it on a different lower and did a full mag dump with no problems. Back on the original lower it acted up again. Who knows why, you'd think switching lowers would have nothing to do with a broken gas ring. Just one of those things.

[Iraqgunz]

Sometimes Gun Voodoo happens. Gun Voodoo is when something occurs, that wasn't previously an issue with no explanation. Do you have other AR's or friends with other AR's? When you say M855, do you mean MILSPEC M855 or some foreign clone ammo?

If so you need to isolate the issue. Step 1 is to replace the buffer with an H buffer. Then you need to get a GOOD BCG and put it into your upper and test it. Isolate the problem. Then I would put your BCG in the other upper and shoot it.

Pay particular attention to the carrier key, gas tube and gas rings. Although I will say that you can run an AR with only (1) gas ring on the bolt.