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Wanted: AR15 Help in LV - Found! / Mystery Solved

Before I spend the $$ to go to one of our sponsors for help I figured it couldn’t hurt to ask here.
Is anyone that’s really good with AR’s (I.e. enough to troubleshoot, disassemble/assemble correctly without forcing, scratching or messing up cerakoting) and willing to donate a few minutes of their time to let me bring my AR to them to look it over and teach me what to look for and what do to address the problems I am having with it?
It’s my first and only AR and outside of how much fun it is to shoot and the really basics of breaking it down to clean, I don’t know much about them and would like to know what to look for and how to fix things so shooting trips out to the desert aren’t completely wasted if things stop working after a few rounds.


I'm in the same boat. I've been watching a lot of YouTube videos. Last trip out I had two stoppages, luckily at the end of the day.

Needed to use a cleaning rod for one stuck case. Learned how to mortar the other one free.
Looks like you're getting the help you need. I'm no expert but I think you'll find most issues are related to buffer/spring or gas block (over/under gassed).
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Just curious as to what problems you were/are having problems with it?
I’ve taken it out twice within the past few months, the first time I was shooting ammo I was unfamiliar with and even though it was brass cased (my rifle doesn’t like steel cased at all) I was getting a lot of FTF and then I got the worst jam I’ve ever had where a live round somehow misfed and got partially wedged on top of the bolt. I got it cleared and it didn’t look like any damage other than a scratch in the cerakote where I messed it up trying to remove the jammed cartridge :mad: I was able to fire a few more rounds without issue so I figured all was well.

When I got home the wife had me doing other stuff, so for the first time since I can remember, I didn’t clean my guns after shooting them, just put them away then forgot all about it until I was invited to go out shooting again. I didn’t get a chance to clean before I left but figured it wasn’t too big of a deal because I was able to fire before I unloaded and put it up.

I put in some different ammo from the crap I had been trying to shoot previously, this stuff was new Fiocci (stuff I had not tried before) and it fired the first 3 rounds okay, but did not fully cycle - I had to manually cycle to eject/load each time, I figured it was just dirty so wasn’t too concerned. After the third round something was not working; I could no longer pull the trigger nor put it on safety. I cleared it and removed the upper from the lower and checked for any obstructions and whatnot; nothing. I didn’t have any lube with me (dumb rookie) but my Dad had some dry lube he uses in other applications that he said is the best he has ever come across. I figured it couldn’t hurt at this point to just see if I could get the trigger/safety to move, so I sprayed the trigger assembly down and tried to move some of the parts in there around - nothing.
Here is a vid made by the builder of the rifle in question:

Dragon40 has some ideas and we are planning on getting together later this week to confirm his suspicions


Geth Prime
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With short-stroking I'd usually be looking at a poorly-aligned gas block, gas port size, and a basic mechanical check of how the action hand-cycles (empty and with brass. Is it smooth, does is drag, does it 'snag' at abnormal engagement points, etc.). I'd also be examining the cycled brass for odd markings (rings, striations, off-round) or other deformations that might be indicative of a problem with the chamber.

On home-built assemblies the gas block is usually where I find the culprit. Usually not centered, canted, not tightened properly, or sometimes just weird blocks that just don't 'fit right'. Anyone that has done a bunch of assemblies has probably encountered that weird gas block. Particularly if you've ever had a friend deposit a pile of parts before you with the request to 'build this' (often without your input on their less-than-quality parts buying decisions). Assuming your block is pinned (per the video), yes, you can get a bad pinning job (it is, after all, still a cut that must be milled very, very properly).

Even on a brand new (quality) BCG you can also have a poorly seated gas key as well. Depending on how 'off' it is, there are a few ways to ID the issue by inspecting the BCG itself for tell-tale carbon spray patterns from the seat of the gas key.

I have seen a few off-spec chambers (one Adams Arms and one Ballistic Advantage). In both cases steel was an absolute no-go, and brass would often 'stick' in the chamber.

I've seen that 'stacked round' malfunction on short-stroking rifles. Seen it both with and without a fresh round being picked up. Different causes in both cases. Hopefully your guide will be able to ID the cause. Look at the extractor and ejector. I've had more than one (quality) brand new BCGs come with 'bad' extractors.

Get a couple boxes of good, high pressure, ammo. Lake City XM193, even Wolf Gold will do. Stuff like Armscor, PMC bronze, and a few others tend be a little lower pressure, and a little lower velocity. Take the possibility of 'not great' ammo out of the equation for troubleshooting purposes. Yes, the rifle should run without issue on basic cheaper ammo, however, that lower pressure may be contributing to a difficulty in identifying the problem. For reference, when fine-tuning an adjustable gas block, I have (anecdotally) made up to a 2-click adjustment to account for lower pressure ammo, to get proper cycle and LRBHO, as compared to full-spec M193.

Finally, proper lubrication is very important. Yes, there are many anecdotes out there from 'I run no lube for 10K rounds' to 'pour 5W-30 until the blood runs clear' and everywhere in between. Some folks will swear by dry lubes, others their favorite vegetable oil of the month. I have my own preferences, but that is not a debate I will enter into herein :) Scrub the chamber, clean the upper, give it a good lube with your choice of quality lube, including the critical components of the BCG itself (inside as well). Particularly if it is a dry phosphate BCG! If you are not comfortable with taking apart, cleaning, lubing and reassembling your BCG, get comfortable, quickly. Watch videos, get a friend to show you, take pictures, whatever. It will become second nature quickly once you have done it a few times.

Assuming that your parts list is the same, or similar, to the one in the video, you have a very good 'parts basis' (CMT/Spikes/BCM/Geissele) for your rifle. However, there is a truism from 6Sigma that no matter how good your quality control is (1) defects will occur, and (2) once people step in your percentage of defects increases. Another way of saying that as may be related to this issue 'Even good builders will have defects', it is inevitable.

And, sadly, none of the above may be the actual issue, or issues. Hopefully your guide will be able to make an actual determination.

Good luck. Glad someone is helping out. Let us know what you find. It may help someone else in the future.
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Thanks for the info! The rifle in the video IS the rifle I am referencing - I purchased it from the person/builder in the video and I have shot hundreds of rounds through it without issue before. I am assuming that when I get some experienced eyes/hands on the thing its gonna reveal that my assumption of the crappy ammo either contributed to a larger underlying issue caused by my ignorance and lack of maintenance or perhaps caused it because I've never had any problems prior.

I have intentionally NOT cleaned or done anything else to the rifle until it can be looked at - I don't want to accidentally fix it and not have a clue what I did and not know how to fix it next time. I anticipate Dragon40 will take 12 seconds to look it over, give me the good 'ol Gibbs slap then tell me how to open my eyes and look at the right stuff & clean/adjust the right things - at least that's what I am hoping, but there may be some broken parts because the trigger nor safety will move.


Geth Prime
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but there may be some broken parts because the trigger nor safety will move.
I did, once, encounter a FCG that was out of spec (ALG QMS). In a friend's rifle, inspected it as the range, it was not cycling correctly and had sticking problems when hand-cycling. Took off the upper, hand-manipulated the FCG and could tell something was wrong. Eventually got it back to the cave, took it out and compared it to a another QMS that I had on hand and could tell that there was a definite difference in the location of the pin hole on the disconnector. That was making the parts not engage correctly. Which, in turn, was causing the rifle to not cycle correctly. Basically the FCG was 'fighting' the BCG as it did not want to go 'down' fully, binding harder along the bottom of the BCG than it should when cycling.

I've also seen not-greatly-milled 80% lowers cause a FCG to not mount correctly, causing similar problems to above, but that is not related to your issue.

Neither of those, however, should cause a brass-sticking issue. And something initially out of spec should have been problematic earlier. Hundreds of rounds down range then these problems start to occur would point me more towards something that has loosened up, come unseated, or even a tiny part in the FCG that might have broken, causing a cascade problem. Too much speculation. But I enjoy troubleshooting things, I'm weird that way :)
separate the upper from the lower, can/will the hammer be manually cocked back? The safety selector should only be able to go into "safe" with the hammer in cocked position.
I don't believe so - when I removed the upper from the lower and sprayed some lube in the lower where the trigger assembly was and tried to manually move parts around in there nothing would budge. I am gonna hold off poking at it any further (and potentially making something worse) until someone that knows what they are talking about gets to see it and tells me what's wrong.

I sure appreciate all of the feedback, offers to assist and ideas everyone has offered - I promise to follow up and let you all know what happened
Spoiler Alert: Nothing exciting or cool

This morning I took my rifle out before going to meet up with Dragon40 with the intention of removing the flashlight I had mounted on it so I could use it elsewhere. While I was moving the rifle around I heard something rattling; not something I would have heard with the wind/earplugs out on the range. While I was tilting the rifle around, opening the bolt, etc. trying to find the source of the rattle a spent primer that had separated from the crappy ammo fell out of the rifle and bingo! no more rattle & the safety / trigger now function properly. No idea where it was; I felt like I looked everywhere it could have been while I was troubleshooting before but obviously not. Going to clean it well, lube it up and get it ready for next time.

Thanks again for everyone's insight and offers to assist!


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Years ago I had a primer blow out and it jammed the gun up badly.

Took a complete take-down to find all the pieces of that primer.

Such a small piece of metal caused a lot of problems.

After I fished it all out, I found the gas block was also loose. (gas tube looked WAY to long was a dead give away!) Ran great after that.