Weird AR jamming issue

[n8thegr8]

I've been having this issue the past few times I've gone out. At first I thought it was ammo because it only happened on the first mag, but it happens every time. It'll happen 2-3 times on the first 30rd mag, then be fine the rest of the day.

Thoughts? It's like a stovepipe/double feed combo or something, I don't even know where to start...

It's a carbine gas system/buffer/spring on a 16" barrel. Could that be it? It's just weird that it's been running fine since I built it 5 years ago and it's just started doing this the last 10 months or so.

 

[Gabriel42]

New buffer or spring recently or any other changes? Clean it regularly? Ammo brand/type?

 

[uncle money bags]

Give us some info on the gun, ammo, lube and round count.

Also, is the round that is still partially in the chamber fired or live?
Just going off the pic I would suspect the extractor and ejector are weak or worn.

 

[n8thegr8]

New buffer or spring recently or any other changes? Clean it regularly?

No changes since I built it a few years ago, and I clean it after every time I take it out.

 

[Gabriel42]

I'd replace buffer spring and extractor spring with new parts and see how it functions or try a different ammo. Someone else may have a better idea though.

 

[aviator41]

To me, the first thing I'd look at is extractor spring or worn extractor. Whats the round count on the bolt?

Do you have another bolt to try in this carrier?

Whats the rim on the stovepipe brass look like? any extractor marks?

 

[dennishoddy]

Could be an ejector issue, could also be short stroking. Just enough to pick up a new round, but not enough to eject.
Borrowing a buffer spring, and a bolt from another gun, or a buddy might let you know where the issue is.

Do you have an adjustable gas block?

 

[n8thegr8]

Let's see

DEZ Arms 16" barrel, M&A Parts BCG, generic carbine length gas system/buffer/recoil spring, YHM folding gas block.

Round count is probably somewhere in the neighborhood of 3000.

I usually shoot whatever .223 I can find at academy or Walmart (federal, monarch, american eagle) or my own reloads. Seems to happen whatever I use.

The partway chambered round is live when it happens (I staged this pic with spent brass since I didn't have the presence of mind to snap a pic when it happened).

I used to use rem oil, but I figured it could be drying out and causing this, so I switched to a combo of slip2000 grease and birchwood casey gun oil.

Sent from my Nexus 5 using Tapatalk

 

[Gabriel42]

Check gas block for correct seating/seal would be another thing I'd check.

 

[aviator41]

Short stroking can be caused by loose or worn gas key, could be the gas tube is partially blocked with carbon, same for gas block and barrel hole