Newly assembled AR won’t eject

AR/M4 AR Technical Discussion
1

Good afternoon. I am a novice at AR builds, so I hope you guys will forgive any overly stupid questions I might have. Though I have been shooting various versions of the M-16 / AR-15 / AR-10, since the early 80s, I’ve always purchased / was issued them, whole.

A while back I bought a CMMG AR-15, in 5.56, which I enjoyed shooting. The only drawback to that rifle, (from a personal aesthetics standpoint), was the retro M-16 style triangle front sight.

I decided to make the rifle girly, for my granddaughter, opting for a Duracoat pink upper, lower, barrel shroud & stock, with various other parts, (grip, take down pins, dust cover, charging handle,etc), done in Cerakote purple. Since I didn’t like the front sight, and didn’t know enough to swap it for a gas block, I just bought a different upper in 5.56 from Bear Creak. I did not fire it in this configuration, but I did test for function, (pre-customization), and it seemed to behave smoothly.

A friend did the Duracoat, and another friend did the disassembly / reassembly. When it was done, I took it to the range to sight it in. I fired one round, and the empty casing did not eject. It was stuck so bad, I had to pop it out with a brass cleaning rod.

One big mistake I made was shooting it dry. I was excited to shoot it, and forgot to oil it. I noticed after the fact that there seems to be a lot of resistance between the slots in the upper, (which has Duracoat inside, as well as outside), and the Ceracote charging handle.

The BCG seems to be working properly, out of the rifle. It has a solid lock on the casing, and the ejection pin has a good amount of spring tension.

Could the added thickness of the Duracoat and Ceracote be adding enough resistance to cause a failure to eject?

One friend suggested I check the head spacing, since the barrel was removed, and reinstalled, but as a novice, I don’t know how to do that. I do not see any excess marring, to the expended casing, save for the scratches on the rim, where I tried pulling it out.

Thank you for your thoughts. I’ll add some pictures, as a reply.

2

Or not…
I’m an old fart, and can’t figure out how to add pics.

3

I’d clean and oil properly and shoot it again. Running an AR completely degreased (probably what they did to coat it) is a variable you want to eliminate before diagnosing. Once that’s done report back.

4

Headspace in ARs is unchanged by removal and reinstallation of the barrel. Of course, this doesn’t mean it is headspaced correctly, though that’s rarely a problem.

I’d lube it as my first remedial approach.

1 Like
5

My first guess is “Bear Creek Arsenal.”

2 Likes
6

It’s as if it’s getting no gas impulse at all, if the BCG isn’t moving at all when firing, even if dry.

7

When the bolt carrier group assembly is out of the rifle, does the bolt move smoothly in the carrier from the locked to unlocked positions and/or are the gas rings damaged?

I once had a carrier with some sort of imperfection inside the bolt carrier that hand cycled normally out of the box followed by a failure to fully cycle on the first round fired and the second shot locking everything up.

Duracoat isn’t the best on internals due to build up potential, but I think you would have noticed that while manually cycling the action.

8

Is the BCG moving at all?
Any chance the gas port was sealed, misaligned, etc?
I’ve had uppers Cerakoted & used Alumahyde & never experienced no BCG movement, so I would start with basic assessment of parts/alignment.
Hopefully, it’s just a lube-type issue.

ETA:
The front sight replacement is likely too far to the rear & the gas port partially blocked. The cap is roughly the thickness of a business card, folded in half. One of the low profile gas blocks I installed included a card to use to approximate front cap thickness.

Best of luck!

9

I haven’t applied Cerakote on anything, but it seems to be thin.

Alumahyde requires a fair amount of over application to build up enough to really stick assemblies together.

Duracoat is thick enough it doesn’t take a lot of excess coats to jam stuff up which makes it a really good product to change furniture color.

10

Understood.

My thought re: gas port & front sight replacement is where I would check given OP’s description of worked with triangular FSB, it was changed & is now a single shot.

Ah, the complexities of multifactorial problem solving….by interweb.:wink:

11

Cerakote, when done properly, adds very little to the dimensions of the part.

12

Need to get PeteBrewer back in for details.

His post may have been modified, but I dont currently see a mention of the bolt not moving at all upon firing. The detail of:

“I fired one round, and the empty casing did not eject. It was stuck so bad, I had to pop it out with a brass cleaning rod.”

Could literally have the extractor pop off the rim(or rip through it) and the bolt carrier group otherwise do all or most of a normal cycle depending on mag in or out and charged mag or not. I tend to check maiden function with only a round in the chamber and no mag to make sure the hammer resets instead of finding out via a surprise burst.

The triangle front sight base that worked was on the factory upper from CMMG.

OP didnt want an original style fixed front triangle frame sight and acquired another upper from Bear Creek Arsenal that has some sort of no integral sight gas block. OP did not test fire the Bear Creek upper prior to having a couple of friends disassemble the upper, apply polymer coatings, and then reassemble prior to the failure during test fire.

I don’t see a mention of whether the BCG was the original from CMMG(that worked live fire out of the box) or if it was included with the Bear Creek.

Which ever BCG was used in the Bear Creek upper, it sounds like it was hand cycled only sans action proving dummies, then extractor/ejector tension reviewed out of the upper after the case stuck live fire failure.

I guess another question further down the line is if the charging handle from the functioning CMMG was used or if it was a new one for the Bear Creek.

13

It took some time to get back to the range, but she seems to be working now, thanks to the advice I got from y’all.

I did play around with parts from my duty rifle, like the charging handle and BCG, and these showed quite a bit of resistance, in the new, painted upper. The BCG from the new gun worked, in my duty rifle, but the new charging handle had too much resistance for me to be comfortable.

I bought some valve lapping compound, and applied some to the inside of the upper, where it looked like the BCG and charging handle were rubbing, then just sat in my recliner, working everything in & out, until it cycled smoothly.

My only negative comment about that process was the ungodly mess the compound left, in my rifle. When I finally got all that cleaned out, I oiled everything well, and shot a few test rounds. The first shot did not fire, showing a light primer strike. Maybe I missed a bit of that mess? After that, 5 rounds went down range, without a hitch.

Time to get it sighted in!

Thank you, for putting up with my inexperience, and showing me what I needed, to get that gun back in the game.

-Pete

14

Good job, team. This is the kind of thing M4C was established for, and it’s good to see the community getting back in touch with its roots.

Thank you for updating us, OP.

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Probably, but double check to make sure the hammer spring is installed right side up before you go back.

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So, looking into an assembled lower, the spring legs should be coming from under the hammer pin, and resting atop the trigger pin.

1 Like
17

Will do.
Thank you!