AR Failure To Feed Problem

[upstate88]

Fresh gas tube (grab a spikes, they are cheap and GTG. low quality ones can rust inside and out very quickly). Also try a buffer spring from another rifle, again something that is easy to pull out of a parts bin and a cheap one can make the gun feel "slugish". This one is weird, but check to make sure the pin in the buffer is still sitting flush.

 

[nwslopoke]

Swap a working complete lower with the upper and see what you get.

 

[Mecanik]

Sounds like under gassing. If that bolt can get behind the cartridge you can almost guarantee it will take the cartridge from the magazine. What it does with it after that is mostly controlled by the magazine. If the tip of that cartridge gets near the chamber it will go in. The feed lips are responsible for that. I would guess that 90% of failure to feeds can be corrected by checking those two items. Does it lock back on the last round? Put one cartridge in the chamber and fire it. If it doesn't lock back you found your problem. How to "fix" the under gassing problem is a bit more complicated and caused by several things already discussed. A magazine problem is an easy fix........

 

[Stomper]

In the picture of your upper it looks like there are burrs on the feed ramps. Is that just my imagination? Check the feed ramps for any burrs that might catch on the case and impede feeding. If there are burrs they need to be polished out with kratex. Look up School of the American Rifle on YouTube. He has some excellent videos on diagnosing and repairing the AR platform.

I discovered it a while ago and love that SOAR channel!!

 

[eldbillbo]

op please let us know what you find out.

 

[cookie]

I gave it a run again on Sunday. I used a new PMag, same problem. Swapped out the BCG from a rifle that has no issues and still had the same issue. So, what I am going to do next is replace the buffer and spring. If that doesn't work, I'll drop in a new lower parts kit (at least the bolt catch and magazine catch).

try a different lower?

 

[Mecanik]

"So, what I am going to do next is replace the buffer and spring. "

I think you're getting close to the problem.....Have you tried firing one round and seeing if it locks back? That would indicate a partial cycle if it doesn't.

 

[Nocaster]

try a different lower?

Why?

 

[nk02442]

This is why people should buy factory rifles.

 

[nk02442]

Why?

That lower is most likely one of the many components which are out of spec.

There are so many variables to account for especially in a junk parts gun thrown together by someone who doesn't understand the system its almost impossible to diagnose without ripping it apart and starting from scratch.

 

[ma96782]

What ammo are you using ?

I was thinking the same thing.

And so.....since you got it home.

1) Clean and lube the rifle.
2) Next range session, use a known quality factory ammo. See if that doesn't help.

IF you're using your own reloads.....you'll probably have to work on that.

Aloha, Mark

 

[cookie]

Why?

Troubleshooting.

 

[Soren]

junk parts gun thrown together by someone who doesn't understand the system

Seriously?!?!?!

 

[nk02442]

Seriously?!?!?!

Dead serious.

 

[Mecanik]

I have put together 8 different AR's all with mismatched brand lowers from various manufacturers and used upper parts from all sources. All of them functioned perfectly without any feeding problems with exception of two of them. Both traced to gas port and buffer combinations. One was over gassed and one under gassed. Once I corrected those problems they both worked flawlessly after that. I used reloads of all combinations and different brands of ammo of at least a dozen types. Ammo brands have never made a difference. Once you understand "dwell time" (The time the bullet passes past the gas port and exits the muzzle) and what's happening immediately after that all of what's going on back in the receiver starts to make sense. Carbine buffers are the most finicky. (That's why there are so many different buffer weights.) What I love about the AR platform is the ease in which these components can be swapped out so I'm sure you will find the problem and learn much from it. It's a wonderful design. I'm on the edge of my seat waiting to hear where the problem is eventually found so keep us informed so we can all learn something.

 

[DirectDrive]

Different ammo pressures (brands, if you will) will indeed have an influence on cycling quality.
It's physics.
But you can TUNE the AR for those different pressures.

The AR in question is most likely under-gassed due to a problem in its gas system or it needs to be tuned for the .223 ammo he is shooting.

 

[eldbillbo]

Since it was once a working rifle I believe the problem lies somewhere from the gas port to the gas block to gas tube to the carrier key somewhere in those components is where the problem is.

If it had not been a working rifle once then many of the other suggested even a out of spec lower, misaligned locking lugs, bures, headspace, mags or tight tolerances just needed to be broke in, chamber needing to be polished etc. could be the issue. A working ar15 should be able to shoot any commercial ammo made for it so ammo should not be the excuse. There is a problem with the rifle.

Check to make sure nothing is stuck in the gas tube blocking it I know that seems silly but its worth a look. The most common reason I see for this problem is a misaligned gas block it just just needs to slip off center a little and you don't have enough gas to do the job. Gas rings are said to cause this problem as well but they have to be pretty worn out and not installed correctly to cause this much problem unless part of a combination of problems.

 

[HB of CJ]

Ejector looks too high? Is this a 80% build? I have not read any other answers. Also try polishing and blending the M4 receiver cut outs with the barrel extension feed famps. Is there also something wrong with the bolt stop? Looks too low.

Just me.

 

[Medic!]

Panic buying preventing you from being able to feed your rifle?




















Did I win?

 

[Soren]

Dead serious.

It's a good thing you're never a jerk, you jerk. You don't know me. You don't know that rifle.