Brass wont extract...stuck in chamber question

[CZB1962]

Let me start by saying I am not all that experienced in the AR platform. I own an AR-15 I assembled with a kit from PSA so I know enough to put the parts together, but not enough to troubleshoot every problem.

My son built .5mm Grendel from the ground up, no kit. We went out to the range yesterday so I could try my new TFO sights and he could test fire the Grendel.

Every round he shot got stuck in the chamber. I would call it a failure to extract. They were stuck so tight that you could not pull the charging handle back by hand. He had to bump the charging handle down on the table to get it to extract the spent case. Once they came out, the case looked pretty normal, no obvious scuffs or scratches. The portion of the neck where it tapers did look a little bulged compared to an unfired round.

If you cycle it by hand, it will extract and eject full rounds with no issue so clearly the cases are expanding and getting stuck.

What are the possible causes? What would you check first to try and solve this?

 

[upchurch67]

Handloads? Overpressure loads can cause the condition you described. If handloads, try factory loads. If factory, try another brand.
Dirty or rough chamber can cause the same thing. I've seen similar issues on bolt guns and pump shotguns solved with just a good cleaning with a high focus on the chamber.

 

[jqunac]

I'm only brainstorming but would 5.56 ammo in a .223 barrel do this?

 

[wsenefeld]

Sounds like a tight chamber or under-gassed. If I shoot my 5.56 or .308 AR rifles, I can turn the gas off (adjustable gas block) and cycle spent cases by hand just fine. Both rifles are thoroughly broken in though.

Try Hoppes No. 9 on a .45 cal brush and scrub that chamber. Be sure the gas block is centered over the gas port and that the gas port lines up with the barrel extension pin.

I'm only brainstorming but would 5.56 ammo in a .223 barrel do this?

He's shooting 6.5 Grendel.

5.56 in a .223 is equivalent to shooting +P+ ammo in a firearm that isn't rated for it. While it may work, it's putting an extreme amount of wear and tear on the components. On the otherhand, it may very well blow/split the barrel if done continually.

 

[bmbutch]

Try Hoppes No. 9 on a .45 cal brush and scrub that chamber.

If that doesn't do it, I've used Flitz Polish & Bore Mop (1 size over) & carefully/slowly polished chamber. Worked for DPMS that had similar issues.

 

[CZB1962]

Handloads? Overpressure loads can cause the condition you described. If handloads, try factory loads. If factory, try another brand.
Dirty or rough chamber can cause the same thing. I've seen similar issues on bolt guns and pump shotguns solved with just a good cleaning with a high focus on the chamber.

These were factory loads and not the cheap stuff. It can't be dirty because it is brand new, but it certainly could need a good polishing.

 

[CZB1962]

Sounds like a tight chamber or under-gassed. If I shoot my 5.56 or .308 AR rifles, I can turn the gas off (adjustable gas block) and cycle spent cases by hand just fine. Both rifles are thoroughly broken in though.

Try Hoppes No. 9 on a .45 cal brush and scrub that chamber. Be sure the gas block is centered over the gas port and that the gas port lines up with the barrel extension pin.

I know being under gassed can keep it from cycling, but I didn't think it should be that tight. I am just thinking of a bolt action. If they were this tight, you could never work the action.

We will try giving it a good polish and see what happens.

 

[oldpink]

I would look at that chamber very closely.
Possibly a burr, rough spot, or even slight gouge that allows the case to expand into it just enough to cause your FTE.
It could even be something as simple as a tiny bit of machining that wasn't fully buffed out at the factory.
As others have mentioned, it would be beneficial to thoroughly clean everything, with special attention to that chamber, but it might be best to carefully examine (using magnification and a bright light) the chamber, both before and after the cleaning to look for unusual fouling or structural imperfections.

 

[Leo]

Try other ammo.

I know that this sounds crazy but I have had experience with soft brass being sticky. I built a 6.5 X 284 bolt action. I formed 100's of pieces of brass out of .284 Winchester brand brass. Never a single problem. When Hornady first started making true 6.5 X 284 brass with the proper headstamp I bought a couple hundred. Loaded with the same bullets and data as always and got to a match, and could not get the bolt open without a cool down. ZERO pressure signs. Finished the match with no problem with the old winchester brass. In the next couple years I met several more people who had the same experience. The brass was just too soft and did not spring back down to size after firing. I am told that later production did not have the problem. As an experiment, I sprayed the finshed ammo that had problems with case lube, wiping off the excess. They would come out after firing with only a little resistance. My M1a Supermatch had the same problem with South African 7.62 Nato also, too soft of brass gets sticky.

 

[sig1473]

Maker of the barrel?

 

[CountryBoy19]

He had to bump the charging handle down on the table to get it to extract the spent case.

I didn't see this addressed yet. Do you mean he was hitting the charging handle on the table? If so, I would advise against that. The charging handle is a relatively weak part of the system and fairly susceptible to damage, especially from that. The preferred way to extract a stuck cartridge is to bump the butt of the rifle down on a table/ground WHILE gently pulling the charging handle to the rear. The "bump" on the ground allows the momentum of the bolt carrier to get things moving and the gentle pressure on the charging handle provides the pulling force to keep things moving to finish extraction.

 

[Strug]

The first two or three rounds I fired out of a new AR I assembled a couple years ago got stuck in the chamber. The extractor actually ripped the rim off of the casing (steel case). My brother (former military) advised that I didn't have enough lube. After I rammed out the second or third round with the cleaning rod, I sprayed the crap out of the chamber with some oil. I didn't have any issues after that. I also believe that the steel case ammo was a contributing factor as I have read before that the lacquer on the steel can can cause the cases to stick.

 

[45Guy]

If you are using hand loads be sure that you have sized the brass all the way to the base.

 

[Ericpwp]

Clean the new barrel.

 

[MohawkSlim]

Once upon a time I took the gas rings off my bolt. After putting them back on I got this issue. I swapped out the bolt (to one with new gas rings) and never had the problem again.

First step - Make sure your bolt travels freely within the BCG.

Stuck in battery after firing is different than ruptured case. The AR is supposed to "unlock" after firing. When it doesn't - and the whole shebang is still locked up - that's indicative of a gas problem. You don't have enough gas pushing the BCG back to unlock it. That could be because the rings are too big and scraping along the inside, it could be because there's simply not enough lube on the bolt/chamber/barrel/etc., there could be a burr somewhere that's hanging it up, or maybe your gas settings just aren't right.

Since it unlocked after blunt force was applied the obvious answer is you need more "oomph" behind it when it fires that ammo. As others have said switching ammo may fix it. I don't like having a gun that won't shoot all ammo so I'd troubleshoot it based on the mechanical issue first. Inspect for burrs, lube the crap out of it, make sure the gas tube and key are clean, and work the action several times. If everything "feels" normal, try shooting again. If it's still messed up... prepare to spend some money because you'll need to start swapping parts out. If this was a parts build it's quite possible something is just a tad off and in ARs, a tad off means boat anchor.

 

[red_zr24x4]

When my brother put together his AR kit it was basicly a single shot. The gas tube supplied with his kit was packed full of white powder.
Check the gas tube.

 

[Ericpwp]

I had the same problem with a new PSA upper. I had cleaned the barrel but not the chamber. I had to beat the rifle to open the chamber. Took it home and cleaned it, shot sub moa the next trip.

 

[The Dawg]

Is the ammo polycoated, or sealed? The sealant could be melting and causing the gun to gum up. I have never heard of this happening on ARs, but it's possible (I'm just brain storming here).

 

[Mr Evilwrench]

I have one AR 5.56 barrel where the casings would get stuck, and I mean stuck. The BCG cycled just fine, and it would try to jam the next round into the occupied chamber. It was definitely not undergassed; the extractor would take a bite out of that casing on its way back. I'd have to drive the casing out with a stick and hammer. The outside of the case was frosty, like it'd been driven into a rough surface and held. I suspect that barrel had been used to fire a good bit of old steel case and been fouled. I ran a chamber reamer in it by hand to avoid headspace issues, and had no further problem.

 

[FlitzPolish]

Gun bore cleaner

If that doesn't do it, I've used Flitz Polish & Bore Mop (1 size over) & carefully/slowly polished chamber. Worked for DPMS that had similar issues.

Thanks for the mention bmbutch. The polish really is helpful for these types of gun applications. Our gun bore cleaner has been specifically manufactured to tackle this problem as well!