Bang, bang, click

Took my DMR-style AR to the range today. Fired about 10 rounds through it and started having problems. Failure to extract/eject. In fact, in many cases the bolt didnt even unlock. Hmmm.

Ok, unload and let’s see whats going on. Pulled the bolt carrier and thought that, since it was new, I hadn’t really lubed it up. So, a quick couple of sprays of CLP and put it back in the gun. No joy.

Disassemble bolt. Aha! Gas rings!

20170903_130229Stagger them properly, re-assemble, no joy.

Alright, now I’m really curious. My buddy is shooting an AR that is also virtually new (less than 50 rounds) so we went ahead and swapped bolt carriers and bolts (yeah, yeah, I know….) Same result. My carrier/bolt worked fine in his gun. Ok, try the ammo. His ammo failed in my gun, my ammo worked fine in his.

Ok, clearly the issue is not in the receiver (upper or lower). It’s gotta be something in the gas system. Couldn’t really do much at the range without proper tools. Came back to the house and took off the forend. Please note this:

20170903_154204Those two screws keep the gas block in place. See how that one is backed out? The other one is also loose. How loose?

20170903_154115.That loose.

“Well there’s yer problem!”

:::sigh::: You know, I have been shooting AR rifles for over thirty years and this is the first time I have ever had anything like this happen. Solution? A dose of Loctite and some torque.

And, really, if I had the proper hex wrenches with me at the range I could have taken care of this right there…so, lesson learned. I’ll head to the range tomorrow to confirm that, indeed, was the problem.


8 thoughts on “Bang, bang, click

  1. Weird. A co worker built a nice rifle recently (I don’t remember the brand but good stuff.)an it just didn’t work. Turned out the gas block was drilled like a hundredth of an inch too small.

  2. Quickie fix: A gas block dimple guide screw and marking pin – mark, dimple, loctite.

    It’s made by EZ Accuracy Gunworks, LLC ( I got mine through Brownells (about $15, IIRC) but searching Brownells for it now returns nada. Next time I log into B-nells I’ll get their part number from my order history and send it to you.

    FYI, Loctite destructs at something like 420F – the recommended way to eliminate Loctite’s holding power when you actually want to remove a fastener installed with the stronger versions (like Studlock) is heat the parts to 410-420F for about 15-20 minutes I forget the exact temprature/time they recommend, but it’s slightly above 400F). This feature makes me wonder about how useful it is for things like gas blocks, but until someone has actual temp data from gas blocks in normal use, I’ll keep using it.

    (Anyone on the more experimentally-minded sites wanna drill a gas block and install a thermistor to get some data?).

  3. Oh yea, been there done that with a self installed gas system. Ran about 1k rounds fine, till the roll pin holding the gas tube came out, lesson learned there.

    Recently the FAL started having issues (FTF) mid mag on the ammo it ran the previous hour. Took it all apart and haven’t found the problem yet. Installed a different gas valve on the front and I’ve dropped the dial-o-gas back to zero and gonna see if I can reproduce the problem.

    Keep those air filters in your house changed Zero, the weeks before Gatlinburg burned last year (and were 200+ miles from those fires) we had smoke so bad that some days I couldn’t see the neighbor’s house 200 yds away. HEPA filters in the house, taped the windows and still had to use some O2 on my elderly mother when she would get some coughing fits. Chunky air is no fun for sure!

  4. If there’s ever a true societal break-down, many people across the US will break open their gun safe and pull out an untested firearm.

    The first time you need to trust your life to your personal defense weapon is not the time to learn that your weapon has a catastrophic flaw.

  5. Simple and cheap solution: drill and pin that gas block.

    DIY if you have the skills and tools, otherwise there are smiths who will do it cheaply. I’ve had a couple of gas blocks ($20) and FSBs ($40) drilled and pinned by Randall at Couple of weeks turn-around, clean worksmanship, I’ll keep sending him barrels until/unless I put my hands to a milling machine and an FSB-drilling jig.

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