Home Forums Hunting & Shooting AR and Tactical Rifles Failure to eject issues

I built a 7.62x39 AR and I’m having FTE issues, but only with brass cased ammo. It was initially doing it with steel cased Tula and a new extractor spring solved the issue. I was out shooting today with my son, and we went through a few magazines in it, not one issue with several different steel cases ammo, but put brass cases ammo in it, and every time it’s a FTE. Gas block is not adjustable, but looks fine and buffer spring is standard factory one with a standard carbine buffer. Any ideas to resolve this issue?

Where's it throwing the cases?

I don’t run much steel case but I believe it is quite common for brass cased ammo to stick in the chamber after running a bunch of steel. Clean the chamber and try again with the brass before you shoot steel.

Between the 3 and 4 o’clock position.

This, or just a rough chamber. The brass tends to form to match the roughness more so than steel, and that causes more tendency to stick when a chamber has rough machining marks (or corrosion pits, but that doesn't sound likely if it's new). Good news is that it's a relatively easy fix with a chamber hone in most cases, if you have a gunsmith who knows what he's doing.

If it's a rough chamber, you can see evidence of it on the fired brass if you look carefully at the case body.

Edit - on second thought, please clarify - does the fired case not come all the way out of the chamber, or does the case stay stuck in the bolt and it tries to feed a new round? My comment above is for the first one, but the second one is a different issue that is most likely a bolt or extractor problem.

What weight buffer? Buy or borrow a heavier buffer, I am willing to bet it solves the problem

Who's barrel?

When it shoots brass it’s pretty much a double feed type. So it tries to put a new round in the chamber and the empty case stays in the bolt. The upper is new, and I did not notice issues with the spent brass casings. The mouth of the case has a dent in it, it so does all of the steel casing it shoots just fine.

It has just a standard H buffer in it. It’s what came in the kit I bought

It’s a Kari’s Guns upper. I was going to build a 6.8, but decided to buy something to just play with. Between the lower, build kit and upper. I think I’m $400-$425 into it. The red dot adds another $100 to it. I’m honestly fine just shooting steel case ammo in it, my son on the other hand, thinks dad needs to shoot more expensive ammo through it. That’s what my 6.5 Grendel is for though.

This. A bore snake is your friend.

kwg

I think the problem is a rough chamber or feed ramps at least is the issue issue. I went out again today with a clean chamber, and a heavier buffer. First mag I ran through it was all brass, damn thing was a single shot. One shot and failure to eject, clear it and fire again, same thing. I put in a new mag with all steel casing, not one hiccup. I looked at the brass from the ones I had issues with, and there are rough spots on it. I got home and broke the AR down, and put my pinky on the feed rails, darn near cut my finger it was so rough. I guess I'll brake out the Dremel and give it a nice polish. The only problem, I won't be able to hit the range again for several weeks.

Hudge,

This could be the excuse you need to get a bore scope.
Here' the one I picked up off Amazon, $50.00:

https://www.amazon.com/gp/product/B07XDYN296/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

Teslong Rifle Borescope, Short Focus Gun Barrel Camera with Side-View Mirror.195 inches Caliber for All Barrel Inspection, Compatibale with Android, Mac, Windows, Linux, 1.0 Megapixel

The first thing I'd try is a lighter buffer.

Sounds to me like the extractor is jumping the rim on the fired case. Look for aggressive extractor marks on the rim of the fired case, to confirm.

If that's the situation, a heavier buffer will retard unlocking/extraction a bit.

I've had that situation with 5.56, and an H3 buffer got it sorted.

If the empty case stays in the bolt it might be under gassed/powered. In other words it sounds like it’s short stroking. Load one round and see if it locks back on an empty mag.

No it was fine with running one in the Mag and then it locking back. It’s only when more than one that is brass cased in the magazine that it acts up.

No worries though, I ordered a new gas tube and gas block for it.

Gas port is the problem.. 1/8 drill bit, drill and open up the gas port. My buddy went round and round with a 450 bushmaster. New gas tube, new gas block, buffers etc. Still didn’t fix it. i talked to Deflave about it short stroking and failure to eject. He said open up the gas port. My buddy did and All problems were fixed and ran like a champ.

.125" is pretty big. I'd start with a #41 (~.096" IIRC) and work up from there.

I agree, start just a bit bigger... if not you go from not extracting to wanting to rip rims off from too much gas.