Erratic Ejection Angle + Bolt Locked behind Live Round

[Scout Actual]

Hello all,

I've got a problem I'd like some help with. I just recently built a new AR-15 from the ground up. My experience level is that I've built 2 AR's from the ground up (except drilling/reaming taper pin for FSB/Gas Block) and done modifications to a DD rifle. The parts of interests are Spike's Tactical with a DD Barrel, DD Gas Block, and Geissle SSA Trigger. Complete parts List below:
- Spike's Tactical FDE Stripped Lower/Upper combo (FA & Cover installed)
- Spike's Tactical LPK (minus fire control group)
- Spike's Tactical T2 Buffer, Buffer Tube, Spring, QD Receiver Plate, Castle Nut, Melonited Gas Tube
- Spike's Tactical NiB BCG
- Geissele SSA Trigger Group
- Daniel Defense Lightweight profile, Mid-length, CHF, Chromed, 16" 1:7 Barrel
- Daniel Defense Superior Suppression Device
- Daniel Defense Low Pro Gas Block
- BCM KMR13, Cerakoted Magpul FDE @ Dobb's Defense
- Magpul MBUS Sights
- Magpul STR Stock, FDE
- AXTS Raptor Charging Handle
- Troy Ambi Mag Release
- BAD-ASS Ambi Safety w/ Standard & Hybrid Lever
- Stark SE-1 Grip
- Vortex StrikeFire Non-Magnified Red Dot
- ErgoGrip Keymod Enhanced Angled Grip
- Noveske QD Direct Attach Swivel Mount

I took it out for the first time yesterday and at first I thought everything was fine. However I had two instances of the same failure (in a total of about 200 rounds fired). During a string of fire (perhaps 0.5 seconds between rounds, plenty for everything to settle) I had the bolt lock up in a mostly closed position. The bolt is about 1/8" out of battery. There was a live, unfired, round in the chamber at this time. The field expedient fix was to mortar the gun to let inertia loosen the bolt.

Luckily a friend happened to be filming me while this happened. See slow-motion, 240 FPS, Dropbox video below (pay no mind to my terrible trigger reset... I'm a relative newb). Also I've screen-grabbed & cropped a pic of the bolt in battery during normal operation and out of battery (basically the failure) shown below.

Dropbox: Slow-Motion 240 FPS Video

In Battery Photo
Out of Battery Photo

Speaking to a few guys at the range a conclusion was reached that, in the failure case, the bolt is closing on the round without the extractor making it over the rim of the cartridge but is rotating enough be stuck. Some suggested that there might be wrong with the extractor spring and that it should be replaced. Since it is such a cheap fix I already have new springs (mil-spec Spikes in old case, David Tubb springs in the new case) on order.

After looking at the video evidence it is also obvious that I've got erratic and inconsistent ejection. Sometimes the rounds eject at 5 O'Clock with little rotation, sometimes they eject at 3 O'Clock with lots of rotation. Could these 2 problems be related? Could the gun be undergassed and that is why the extractor sometimes doesn't make it over the case rim?

Thanks in advance!
Scout

[Computalotapus]

If you have another rifle start with swapping the BCG for one that you know you don't have issues with. If it works then swap the extractor spring and bushing.

[Dstrbdmedic167]

Agree with comp. Also what ammo were you using? New or reman new?

[GaSwamper]

Welcome Scout, good job on presenting your problem alota guys say " hey I got a problem. Whats wrong?" lol. I agree to swap the BCG to one you know functions right first. If that doesn't fix then maybe swap the heavy buffer to standard. Of course a quick check of the gas block to make sure everything is lined up, I doubt port size issues but ya never know. What ammo were you running and have you tried different brands/loads?

[GaSwamper]

Agree with comp. Also what ammo were you using? New or reman new?

I type too slow!

[Dstrbdmedic167]

I type too slow!

No you just made a better quality post.

[alamo5000]

Upon thinking about it more there could be a number of issues.

Here would be my non expert check list.

As others have said ammo. If it is out of spec it won't seat all the way in the chamber and will create gas leaks which could chain react to short strokes or whatever.

Possible head spacing check? Inspect the chamber of your barrel.

Make sure the gas block isn't moving around under pressure.

Obviously check the bolt/swap it to see if the problem persists as others have already said.

[Stone]

Re-check headspace(assuming you did a first time) Cycle the rifle a few hundred times by hand. Give the chamber a good scrub down and try some different ammo...

[Eric]

try some different ammo...

Exactly. One of the first things to look at for something like this, especially if reloaded/remanufactured.

Next up would be to try a different complete BCG. Confirm the gas key is not binding up on the gas tube.

Always start troubleshooting with a clean and well lubed rifle. Hit the chamber with a chamber brush, ensure there isn't something wedged in the chamber or lugs, like a primer chunk.

[Stone]

"Speaking to a few guys at the range a conclusion was reached that, in the failure case, the bolt is closing on the round without the extractor making it over the rim of the cartridge but is rotating enough be stuck."
Are you 100% sure that those 2 rounds fully seated in the chamber? When you mortared the rifle did it pull the round out?

[SINNER]

How many rounds were in the magazine at the times of failure? I have seen a too weak buffer spring cause this very issue only when mags are near capacity. The drag on the bolt from the pressure of the rounds below slows it down enough to cause it not to go into battery.

Did you attempt to use the forward assist to get the bolt into battery?

If not that I would look hard at the fitment of the extractor in the bolt. A bolt machined on the small side of the spec with coatings applied can and will restrict the movement of the extractor although if that was the case it would normally cause issues from the onset and not be so random. Also when the extractor is restricted it will normally cause damage to the rim of the round.

[Scout Actual]

BINDING
The bolt runs smoothly in and out. I opened it up and ran the bolt forward and back by hand it felt smooth. I can push the bolt into battery with one finger.

HEADSPACE
I checked the headspace when I first built it and again just now using Forester GO (1.4636 MIN) & NO-GO (1.4736 MAX) gauges. It goes into battery on the GO and won't go into battery on the NO-GO. I have not ever tried to actually measure the specific headspace value (on any AR).

AMMO
I was using remanufactured brass .223. I didn't try other ammo. I will when I can

BCG
I CAN swap BCGs but I didn't. I will when I can.

EXTRACTOR
The extractor is difficult to actuate. In fact, I can't get the retaining pin out. I have a DD bolt that is easier to actuate and I was able to get the retaining pin out easy-peasy.

MAGAZINE
I can't know for sure right now, but judging from the video. There were probably 19 rounds in the magazine + 1 in the chamber. I know which magazine I was using on one of the instances of failure but not the other :/

[Dstrbdmedic167]

I'm going with improperly sized brass since it was reman ammo. I've had a similar issue and realized my die got off and wasn't reforming the brass enough. Had a time with it until I figured out that's what it was.

[Jerry R]

AMMO
I was using remanufactured brass .223. I didn't try other ammo. I will when I can

This is a flag I see based upon only two failures in the batch. If a case is not resized properly (or not at all) and had been fired in a max spec (or out of spec) chamber they can "bind" in a chamber that is minimum spec or close to it.

Totally unrelated --> If you get into reloading, I would suggest an RCBS Small Base 223 sizing die since you have multiple chambers you will be reloading for. This die sizes to factory minimum specs and rounds will drop into any spec chamber. Will shorten case life a little, but reliability is more important to me than one or two extra reloadings on a case.

Let us know when you try different ammo - would try factory only until problem determined.

[Scout Actual]

It will be at least 2 weeks until I can get outdoors to shoot I can probably get to an indoor range this week. Hopefully I will be able to do the comparison effectively in the little booth. FYI I own two different brands of remanufactured ammo and I will buy some factory ammo and compare all 3 ejection patterns.

I can also try the remanufactured ammo in another rifle with a new DD barrel and another with a 1000 round DD barrel.