Failure to Eject

SoMD_Gen4 · Feb 3, 2014

So I went to the range this weekend to tryout my newly assembled AR-15, but ended up having a FTE issue. I had planned to sight in my EoTech, but after firing the first round, the brass casing didn't eject.

I took the BCG and charging handle out, cleaned them, and re-lubed them and tried again. Same result. After firing downrange, I have to pull back on the charging handle to eject the brass.

Again I took it all apart, and tried to inspect whether the gas tube and gas key on the BCG were lining up, and they seemed to be. But it also looked like the gas key had no residue in it, although I had only taken two shots with it, i would assume if it was lining up properly, there would be atleast a little crud back there.

I tried one last time with no luck. I took the rifle home, and completely disassembled the upper minus taking off the barrel nut and barrel. I took the gas block pin out of the gas block, inspected the holes to make sure they were lining up and inserted a new gas block pin. I made extra sure that the gas tube was lined up as straight as possible while re-tightening the hex key on the gas block as well. I haven't shot it again after the reassemble, but any thoughts as to what else it could be?

jimbobborg · Feb 3, 2014

Not enough lube.

Inigoes · Feb 3, 2014

Caliber? 5.56, or something else?

Lubed liked a greased pig, for break-in?

Ab_Normal · Feb 3, 2014

Could you tell if the BCG had moved to the rear at all when you shot it?

There won't be much crud back there a lot of times with only 2 shots.

SoMD_Gen4 · Feb 3, 2014

Inigoes said:
Caliber? 5.56, or something else?

Lubed liked a greased pig, for break-in?

Yeah- 5.56 caliber, and I thought it was lubed up like hell, maybe ill try even more when I re-shoot it.

SoMD_Gen4 · Feb 3, 2014

Ab_Normal said:
Could you tell if the BCG had moved to the rear at all when you shot it?

There won't be much crud back there a lot of times with only 2 shots.

Not sure if I could tell or not. I was pulling back and "recharging" persay to get the brass out.

Inigoes · Feb 3, 2014

SoMD_Gen4 said:
Yeah- 5.56 caliber, and I thought it was lubed up like hell, maybe ill try even more when I re-shoot it.

Use factory ammo too. Reloads only complicate the troubleshooting.

Ab_Normal · Feb 3, 2014

You may want to measure the distance of the port from the shoulder on the barrel as well as the port from the face of the gas block. Some need a spacer to align them properly. Also mark the location of the ports with a sharpie so you can get a rough idea that the axial alignment is correct when they are assembled.

Ganegrei · Feb 3, 2014

jimbobborg said:
Not enough lube.

If I had a dollar...

erwos · Feb 3, 2014

jimbobborg said:
Not enough lube.

That's not going to be the problem for a clean rifle. More likely, his gas system is broken somewhere down the chain. I lean towards a gas block misalignment.

BradMacc82 · Feb 3, 2014

erwos said:
That's not going to be the problem for a clean rifle. More likely, his gas system is broken somewhere down the chain. I lean towards a gas block misalignment.

Agree.

Low profile gas block or fixed FSB?

(Likely low profile, but clarification never hurts.)

SoMD_Gen4 · Feb 3, 2014

BradMacc82 said:
Agree.

Low profile gas block or fixed FSB?

(Likely low profile, but clarification never hurts.)

Yes, low profile gas block. Also shooting factory ammo, no reloads.

John from MD · Feb 3, 2014

+100 gas block misalignment or blockage. Lay the gas block on the side of the barrel with the gas port and hole in the block are side to side. Mark the barrel with a pencil as to where front and back of the block are and also a line to show the centerline of the barrel with relation to the gas port.

Check the block to make sure it is drilled through and there is nothing blocking the holes.

This is basic set up but it will work in most instances.

John

TrappedinMD · Feb 3, 2014

Do you have a free floated hand gaurd/Rail? I know when i assembled my gun I had to shim my gas block .025" (if i remember correctly) to make up for the part from a typical hand gaurd. I have a low profile clamp on style adjustable gas block. Also its not adjustable is it?

SoMD_Gen4 · Feb 3, 2014

TrappedinMD said:
Do you have a free floated hand gaurd/Rail? I know when i assembled my gun I had to shim my gas block .025" (if i remember correctly) to make up for the part from a typical hand gaurd. I have a low profile clamp on style adjustable gas block. Also its not adjustable is it?

Yes- YHM Diamond handgaurd. The LP Gasblock fit pretty snug so I doubt it needs to be shimmed. I will repost after I get it back on the range and test out the rebuilding of the gas block/tube assembly.

Ab_Normal · Feb 3, 2014

SoMD_Gen4 said:
Yes- YHM Diamond handgaurd. The LP Gasblock fit pretty snug so I doubt it needs to be shimmed. I will repost after I get it back on the range and test out the rebuilding of the gas block/tube assembly.

Has nothing to do with the fit. It has to do with moving it away from the shoulder of the barrel.

What length gas system are you running?

DoubleTap007 · Feb 3, 2014

For the gas block, if you back out the front (Closer to the received) set screw, and spin the gas block around, you are able to see the alignment of the gas port and the hole in the gas block, you can then see if you need to shim the gas block back off from the shoulder of the barrel.

Erno86 · Feb 3, 2014

The spring for the detent that holds the recoil buffer & spring is missing? Wrong hydraulic buffer?

jimbobborg · Feb 3, 2014

You're using an AR-10 recoil spring and not an AR-15 recoil spring? Yes, there's a difference and using the AR-10 spring in an AR-15 does exactly what's happening to your rifle. Did you put the lower together yourself?

SoMD_Gen4 · Feb 3, 2014

Ab_Normal said:
Has nothing to do with the fit. It has to do with moving it away from the shoulder of the barrel.

What length gas system are you running?

It's a mid-length gas system on a 16" barrel. The barrel is a Spikes FN 16" CHF 1:7, 5.56 NATO

Failure to Eject

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