AR15 not ejecting spent cases

New to this forum as I am a benchrester and bolt gun owner. A friend
has a Bushmaster AR15 that he wants me to sight in (new scope) for
him. He says that the gun has started not ejecting the spent cases
when firing. He is not a handloader so he is using factory ammo.
What should I look for? I do handloading if that is necessary.

Any help will be greatly appreciated!!!!

Thanks
Les Morgan

Need to find out where it is failing.

What happens when the shot is fired?
Does the bolt complete a full cycle?
Where does the spent casing end up after the shot?
Does a cartridge (or casing) eject if you hand cycle it?

If the bolt isn't cycling, you may have a bad gas tube or gas port, or it may be misaligned.
If the bolt is cycling and the gun is trying to feed another round but isn't ejecting the casing, it would probably be a problem with the ejector or extractor.

Called owner of rifle and asked more questions.
He said the bolt is cycling but it is leaving the fired case in the chamber.
Overriding the extractor!
He has tried several different factory loads.
He also said that he has tried a different upper and a different bolt
both with the same results.

Thanks again
Les

Different upper and different bolt with same results?

Try different ammo.

What is the type of barrel and length? Has he added or changed any of the stock parts lately?

Just to make sure I understand you, he tried the same bolt in a different upper and it still failed to extract or he tried a different bolt in the same upper and it still failed to extract?

He said the bolt is cycling but it is leaving the fired case in the chamber.
Overriding the extractor!
Sounds like the chamber is tight or rough.

But if the problem persists through otherwise functional uppers ...
Hmmm ...
I can't think of a possible problem with the lower that would cause this. Maybe a buffer assembly issue? Don't see how that would affect the extraction on a good upper, though.

Says he's tried different uppers AND bolts. Must be buffer tube or ammo...or two uppers with bad extractors. :scrutiny:

Any advice on a good load for this rifle? Have plenty of cases and 52gr
and 69gr Sierra Matchkings. The rifle is a Bushmaster with what looks
like a heavier than normal barrel.

Les

Says he's tried different uppers AND bolts. Must be buffer tube or ammo...or two uppers with bad extractors.
I thought maybe underpowered buffer spring or far too-light buffer (or a combination of the two) might make the bolt retract too quickly and let the extractor jump the rim but have never heard of this happening. That's the only possible thing I can think of being attributable to the lower.

Tell us more about the gun. Has your buddy done any 'work' on it? Are you sure the other upper he tried was good?

Try a new extractor and spring...Don't forget the little rubber thingie.

Tuner

A long shot, but make sure the "key" is tight.

Not sure if I'm calling it correctly, but it's the short gas tube on the bolt. If it's a little loose you'll have a single shot rifle, but it will still extract properly when manually cycled.

Morgan said:

Not sure if I'm calling it correctly, but it's the short gas tube on the bolt. If it's a little loose you'll have a single shot rifle, but it will still extract properly when manually cycled.

Good call Morgan! Been a few years since I worked on the rifles...
Ain't gettin' old a pisser though?:rolleyes:

Keep yer powder dry!

Unless there is more to this story, I find it hard to believe that he has tried different uppers and bolts and is still having the same results. Not saying he's a liar, just never ran into this before.

A few questions for you:
Where did he get the other upper?

Is his ammo kept clean or are the casings corroded?

My suggested course of action:
Start by replacing the gas tube, it's probably the cheapest part involved.

Then look at the chambers on both uppers for roughness. Then remove the upper from the rifle, and place a round in the chamber, then tip the rifle so you can remove the casing from the chamber. Clean the chamber area as well as you can. He may have a punched primer or something else in there holding things up.

Next I would check the extractor and ejector on both bolts.

The gas tube is really the only other place to look.

Good luck and let us know where you end up.

Any rifle with a plunger-type ejector has the potential to get the ejector jammed due to dirt, brass filings, etc. That is probably not the case here due to the symptoms, but Ive seen it on quite a few instances where you have to pull the bolt and free up the plunger to get it to eject.

That's why a fixed ejector is more reliable than the spring loaded plungers, imho. Probably cheaper to make since it only needs a straight hole drilled for the round plunger and a cross pin. FWIW

Yet another good call. With all this input, the lad will have his little
black rifle up and runnin' in no time.


Cheers!
Tuner

Many variables in this scenario.

A legit upper comes with its own bolt and carrier; some guys call a new upper a shell/bbl assembly of unknown provenance
The cartridge could well be getting extracted and going right back into the chamber if the ejector is jammed; and
The bolt carrier key needs to be tight and screws peened
gas tube needs to be mated to bolt carrier
both above need to be checked to make sure gas pressure is sufficient.


It could be that gas is not blowing the carrier back hard enough and/or ejector jammed resulting in ctg going back into chamber. He has not mentioned the thing stripping a new ctg and jamming that under the fired case, a classical M16 jam, has he?

Just a few ideas...

Being new here I hope this doesn't come across wrong. Not at all to be a smart ???, but make sure he gets and keeps it oiled well. I have that problem with my colt AR when she starts to get anything less than soaked. I didn't see anyone even mention that, so I thought I would go ahead and share it.

Took the rifle home for the first time last night and started looking the rifle
over. Removed the bolt and Barrel/upper assm. Bolt raceways seemed
dry and had a black dry residue, cleaned raceways. Using a small flashlight
the chamber area did not look clean, almost looked like rust in the chamber
area. Used JB bore cleaner on a chamber mop and scrubbed the chamber.
Looked better but I am still not pleased with how it looks. I think I will try
a little 0000 steel wool on a bore brush tonight to totally clean the chamber. Are there any particular areas that I need to make sure to grease when I put it back together? Also how do I check to see if the
bolt tube mentioned above is loose?

Do you have any favorite loads for sierra 52mk's-- Have H335, H322,
N133, and IMR4064 powders.

Remember I am a Panda 6PPC shooter so any help on this gas gun is
greatly appreciated.

Les Morgan

Not at all lad! You made another good point. When I was snoopin'
and scootin' in the paddies, I kept mine WELL-oiled. I wasn't happy
unless it was slingin' oil in my face. A clean "Sixteen" is a happy
camper.

Les, another thing to check/do is to clean the carrier key with a
worn-out .22 rimfire bore brush, and put a drop of CLP Breakfree
in it. A drop in the gas tube wouldn't hurt either. Turn the
upper muzzle down to let it travel.

Rust in the chamber??? Hmmm. More likely carbon fouling.
Ball powder leaves a residue that, over time and with neglect,
can become about as hard as the steel that it's on. Very hard
to remove...and sometimes impossible if it's in the bore grooves.

Watchin' this one...Luck to ya!

Tuner

Also how do I check to see if the bolt tube mentioned above is loose?

That is called the bolt carrier key. Grab it and try to wiggle it. It is attached to carrier with two screws that should be peened with a couple of punch marks so the screws won't back out.

If it's solid, then you need to look and see if it mates with the gas tube.

Unless my reading comprehension skills have flown the coop, I read that this is happening with two uppers and two bolts.


Sounds like one upper was dirty. Wash it out well with brake cleaner and the little hose. Get into the barrel extension really well. Scrub everything if it is really that bad. Use a chamber brush with a patch on it and some GM Top Engine Cleaner. Disassemble the bolt carrier and blast it out with the brake cleaner too. Every part of it. After it dries, re-oil...a little on the rings, make sure they're staggered, a little on the ring behind that, a little on the locking lugs, a little on the sliding surfaces of the carrier. It does not need to be WET with oil. 24 grains of RL15 and a Rem 7 1/2 primer ought to work.