Hi, all.

I should have posted this weeks ago, but I have been lazy. This past summer I build my first AR15; however, when I went out to shoot it, I had quite a few problems. I suspect they are barrel/chamber related.

All in all, I shot about 200 rounds at this range session. In the first magazine, I had about 6 consecutive casings get stuck in the chamber, resulting in another round trying to feed behind it. Removing the magazine and cycling the bolt did not extract these. In fact, the extractor would strip off the rim of the casing when I tried, leaving the casing in the chamber. In one instance I had to "mortar" the rifle to get the bolt back after releasing it on the casing. These first 6 or so casings' primers stayed intact. To remove these casings, I had to lock the bolt back and shove a cleaning rod down the barrel with some force.

I switched magazines, and the problem went away for a while. This magazine was already loaded when I got to the range. I believe this may have been the result of bullet set back because, after assembling the rifle, I chambered several rounds several times to function check it and also test the forward assist (this was probably stupid on my part).

BUT later in the shooting session, I had about 3 or 4 casings get stuck in the chamber AND the primers popped out of the back of the casing and into the breach. These were not consecutive rounds fired; these occurred sporadically during the rest of my 194 or so rounds.These rounds were fresh out of the box and had never been chambered before loading them to fire. I had to use the same method of ramming a cleaning rod down the muzzle end of the barrel to clear these. Does anyone know what I can check to troubleshoot this? I suspect the chamber may be too tight or the head space may be wrong, but I am not familiar with these or how to measure them. I also am a bit scared to test fire the rifle if this is overpressure.

If I remember correctly, this happened with both Wolf Gold Brass cased .223 Rem and brass cased Independence 5.56mm ammunition or maybe Federal 5.56mm (this happened about two months ago, so I can't remember for sure). The only ammo that functioned flawlessly was green steel cased .223 Monarch brand ammo from Academy (I assume this is because steel cases do not expand as much as brass).

Thank you in advance for any advice!

List of relevant parts:
Barrel - Radical Firearms 16" Match Grade 416R Stainless Barrel - SOCOM Profile - 5.56NATO - Mid-Length
Gas tube - Armalite Mid-Length Gas Tube
Gas block - Midwest Industries low profile gas block - .750
Muzzle Device - Lantac Dragon "Zero Recoil" Advanced Muzzle Brake
Upper - Spike's Forged M4 Upper Receiver Assembly SFT50M4
Bolt/carrier - Spikes Tactical AR15 Complete Bolt Carrier Group - 5.56MM
Buffer tube and spring - Advanced Technology Mil Spec Black Tube, Spring, Buffer, Locking Ring & Nut

Here are pictures of the casings I saved. I think I also took pictures of the casings stuck when they were stuck in the chamber, but I forgot to upload them to photobucket. I can add these when I get home.
Casing without popped primers. Notice the stripped rim.


Casing with popped primers.

Stuck cases in the chamber may be the result of a dirty chamber, not necessarily a out of spec chamber.





You didn't mention what ammo you are using.  If these are reloads, the primer is most likely not crimped in which may lead to primers popping out.  Also, if hot reloads, the primer may want to pop out.  



ETA:  I just reread the OP, I see that the ammo was different types and apparently new, not reloaded.  So, never-mind.




 

Thanks for the feedback. I don't think it was caused by a dirty chamber since this is the first time I had ever fired the gun, and it was made from brand new parts.

If the gun was new it most certainly must be cleaned before firing.  There will be "stuff" left inside the gun from the manufacturing and assembly process.  If you fired it before giving the chamber a good scrubbing, you will likely get malfunctions.  In addition to a bore brush, you will also need a chamber brush.

OP,

Dennis has a good point.  Cleaning and ammo are 2 of the most common causes of the problem you describe.

A new build needs good cleaning since there is often assembly lube in place and feeding and extraction can be affected.
Also, all of the ammo you mentioned is second tier (except the Federal) and it may or may not be good ammo.  You should start from the optimal position on a new build break in with a really squeaky clean and well lubed tool, and highest quality ammo.  Then, if you have a problem, you can rest assured that it is something else.

Use a chamber brush and CLP and really clean it.  Then use a top tier ammo to check function (Federal, Winchester, Remington) and see how it goes. Then see what other ammo your rifle likes as well.  All this takes time and thought and is well worth it.

Good Luck!

Thanks for the suggestions, guys. I will try giving it a good scrub down (I think I lubed it up beforehand, but I don't think I used any solvent) and getting some good ammo. Is it potentially dangerous to shoot this gun though? I am just a bit concerned about firing it again even if it's to troubleshoot. It might be a while before I get a chance to fire it again and report back, but I'll update when I do.

If you have not check your headspace.

Blowing primers is high pressure period. No amount of cleaning, especially if you put 200 rounds through it will make a difference. There is something seriously wrong with your rifle. Stop shooting it immediately and contact the barrel maker.

To anyone reading this, if you're getting stuck cases, rims ripped off upon ejection and blown primers STOP SHOOTING  that rifle. The reasons have to be discovered as to why this rifle and ammo are behaving this way. A KABOOM is possible if you continue to shoot as if nothing were wrong.

This barrel and bolt needs to be sent to the barrel manufacturer for inspection, repair or replacement. They will probably want to know who's ammo was used. Some of the ammo listed is junk and probably going to void your warranty. I think Independence sells reloads, I will never shoot steel case ammo from any rifle I own.

Thanks for verifying the dangers. I decided not to shoot it again and simply contact the barrel manufacturer. I got an RMA number and sent it in the other day (I sent the entire upper).

I got a call today saying the gunsmith had honed the barrel and fired two magazines through it without a failure. I'm not familiar with honing, but from what I've read, it's like a more precise version of reaming the chamber.

It's currently in shipping back to me. I'll update again once I get to shoot it (hopefully it doesn't blow up).

I got my upper back yesterday and shot around 200 rounds out of it without a failure. Hopefully, it stays that way. It appears to have been caused by a tight chamber.