AR cycling issue

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justin22885 said:
youre trying to educate a bunch of people who believe what they heard on youtube more than simple physics.. you can overlubricate a rifle and then i get this line of misinformation about how the ar-15 is a "bearing" or some crap like that, not realizing you can put too much lube in a bearing too

i think they need to read up on a thing called hydrodynamic drag which occurs when bearings are over-lubricated which results in drag on the moving components that has to push its way through the piles and globs of dripping gun oil which can have as adverse of an effect as running dry
Click to expand...

Over lubing an AR with oil doesn't cause malfunctions
https://www.youtube.com/watch?v=p9bOT_d60LM

There is no reason to soak a rifle like this, but it shows that too much lube isn't the problem
 
Gas block and gas tube has never needed cleaning. It gets extremely hot air smashed through it at 10k+ PSI every trigger squeeze.

Any issue I have ever had with ARs not cycling is the gas key being loose or clogged or the bolt being dry.

I also once built my first upper and the problem was that the barrel was not dimpled so the gas block was not on properly.

It could be something is out of spec (like BCG) but doubtful.

Try a different ammo and check the gas key, clean the Bolt and BCG thoroughly, check alignment of gas holes and pour on the lube liberally. I take brand new or dry bolts, put them in a ziploc just big enough to fit them, squirt lube on them and shake the bag up and let it sit for a few hours or days (depending on when I intend to shoot it next. That allows it to get all over it.
 
justin22885 said:
no, it shows one video, one magazine in a controlled environment and you assume this disproves documented physics because omg.. you watched it on youtube
Click to expand...

The video is only a sample of one, but it's an extreme sample, far beyond the amount of oil we're seeing in the photos posted by OldSchool. In fact, the amount of lube on the OldSchool's carrier is nothing compared to the lube and fouling I've had build up on the carrier of my own AR and it never caused a malfunction.

The video was made by Larry Vickers, a well vetted and trusted source of information and knowledge within the community. He has years of advanced training and experience and has been there done that. If you think the results achieved in the video is a fluke, then repeat the test for yourself and see what happens
 
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MistWolf said:
The video is only a sample of one, but it's an extreme sample, far beyond the amount of oil we're seeing in the photos posted by OldSchool. In fact, the amount of lube on the OldSchool's carrier is nothing compared to the lube and fouling I've had build up on the carrier of my own AR and it never caused a malfunction.

The video was made by Larry Vickers, a well vetted and trusted source of information and knowledge within the community. He has years of advanced training and experience and has been there done that. If you think the results achieved in the video is a fluke, then repeat the test for yourself and see what happens
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you have way too much faith in youtube videos, i dont care if its larry vickers, santa clause, or jesus doing the youtube video, running weapons dripping wet with lube is bad information and telling someone to overlube it an attempt to fix the problem is just plain stupid

even if overlubricating the weapon managed to get it to cycle, it doesnt fix the issue, the rifle needs to be able to run reliably with the PROPER amount of lubrication and all youre doing by throwing more lube at it, at best, is just masking the underlying problem, not fixing it

adding more lube is bad, bad advice, the proper course of action is to lube it PROPERLY and diagnose the problem from there because the rifle needs to be able to function properly with proper maintenance
 
now, getting back to the issue that was so CLEARLY not a lubrication issue, the OP says he doesnt feel like the carriers going all the way back, and the bolt doesnt reliably lock back then its a short stroking issue

if its short stroking it can be gas rings, loose gas key, obstruction in the gas system, or even a gas leak.. this is all assuming of course these arent some poorly put together low-pressure handloads with a powder that generally doesnt have the pressure required at the rifle length gas system to actually cycle the bolt reliably

gas key can easily be checked to make sure its not loose, the gas tube can be removed and inspected for any kind of obstructions or leaks, a simple pipe cleaner in the gas block should tell if the ports undersized or not drilled completely through, and a simple change of nato spec ammo, or at least decent factory ammo should rule out that issue
 
How do you get "Over lubing will fix the problem" from "Over lubing with oil doesn't cause short stroking"?
 
Seems like we'll have to wait for the OP's next range trip to know what helped and what didn't.
 
Remove your gas block and check the gas port size. You can at least eliminate that and it's easy enough. When you put it back you have to make sure everything is aligned and the pins are installed correctly.
Click to expand...

Easy to say, but how do you suggest he "check the gas port size"?

You can get close if you have a good set of "number" drills and a micrometer -- find the last number size who's shank fits the hole when the next lower number is too big, then mic the shank and you'll be close to the port diameter.

I'd bet against the OP being able to do this. Not to mention the taper pins holding the FSB/gas block have messed up more than a few beginners.
 
is there any reason he couldnt stick a pipe cleaner or copper wire down the gas block from the front to probe the gas port hole?
 
Justin, Briansmith already told you no. Trust him, he actually knows what he talks about.
 
USAF_Vet said:
There's no reason he can't. But there's no reason he should. And a few reasons he shouldn't.
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its a used gun, who knows what parts have been replaced and of what condition those parts were, and what powder has been used in it in the past or how its been cleaned.. it would rule out that possibility with no harm to the rifle
 
The only way I can see the tube and port being stopped up is, it was used only with subsonic that used a very dirty powder... but following up with supers should blow it clear... I would bet on an out of line gas block before a stopped up tube...
 
farmerboy78 said:
The only way I can see the tube and port being stopped up is, it was used only with subsonic that used a very dirty powder... but following up with supers should blow it clear... I would bet on an out of line gas block before a stopped up tube...
Click to expand...
same procedure checks and rules out both, once thats ruled out then you can be certain its BCG related.. thats all im saying, rule out the stuff thats easy to rule out
 
same procedure checks and rules out both, once thats ruled out then you can be certain its BCG related.. thats all im saying, rule out the stuff thats easy to rule out
Click to expand...

Checking the gas port diameter and location are on the list of things to check, but they are down the list a ways for a reason. Those aren't common things to be wrong and checking them isn't trivial, plus there is the risk of collateral damage.

It's like going to a new doc for a checkup and before he takes your temperature and blood pressure he orders a barium enema. A barium enema can be a useful test, but usually he goes there for a specific set of symptoms.

I'm not seeing the symptoms that point to a clogged gas tube, or a misaligned and/or a undersize gas port. The symptoms and diagnostics as reported by the OP are:

1) I like the accuracy I got out of it but it didn't cycle. The shop gunsmith took a crack at it and replaced the BCG group with a Nickel Boron one. It no cycles but not 100% of the time. He says he got 15 rounds cycling fully.
2) Ok, the gas tube got replaced with the BCG and it got a through cleaning.
3) Ok, this is an Eagle Arms AR15A2; 20" barrel (Rifle non-adjustable stock) the upper and lower are possibly the tightest I've ever seen on an AR. The gas rings in the BCG are in good condition. The rifle was extremely dry on it first run when it wouldn't cycle. I've never limp wristed a pistol but that is how I would describe the intermittent cycling I'm seeing now. When we shoot it and it doesn't cycle I can't tell if the BCG isn't coming back at all or just isn't coming back far enough to chamber the next round and is riding on top of the next round. Next I'm going to try drowning the BCG in lube.
4)Ok, still getting weird. Single round in the mag it locks back most of the time.
Running it wet with oil helped some. I wasn't real consistent with the ammo we were using so that is still a variable.
I was however getting these nasty jams more than I like Its almost like its not unlocking and ejecting properly. Listening to the buffer tube sometimes there is no recoil pulse(no spring sound coming from the buffer tube). I'm going to see if I can find someone local to me to look at the gas block and port alignment.
5) its a complete Bolt group there is just a lot of oil on it! Gas tube is new. I keep this rifle separate from my residence so unfortunately I don't have ready access to it for pictures.
Click to expand...

My take on the above is:
1) Too many variables, but the important thing is that the rifle is cycling fully sometimes. That rules out things like no gas tube or no gas port.
2) Gas tube has been replaced, this rules out a clogged gas tube.
3) Intermittent cycling has gotten better since cleaning and lubrication.
4) Single round in the mags locks back most of the time. This rules out a too small gas port. Rifle runs better with more lubrication. The picture isn’t that clear but I am suspecting either the extractor is failing to retain control of the fired brass or the ejector is failing to clear the fired case before the BCG runs forward.

I suspect there were two original problems:
A) The rifle was too dry to function.
B) Bad extractor or ejector.
The bad extractor wasn’t obvious before because the rifle was too dry to work correctly.

The other big variable is ammo. The OP hasn’t stated what type of ammo he’s using or if the results are different with different ammo.

BSW
 
Never stick anything in the gas tube that you don't want taking up permanent residence in there. That goes double for pipe cleaners
 
Checking the gas port diameter and location are on the list of things to check, but they are down the list a ways for a reason. Those aren't common things to be wrong and checking them isn't trivial, plus there is the risk of collateral damage.

It's like going to a new doc for a checkup and before he takes your temperature and blood pressure he orders a barium enema. A barium enema can be a useful test, but usually he goes there for a specific set of symptoms.

I'm not seeing the symptoms that point to a clogged gas tube, or a misaligned and/or a undersize gas port. The symptoms and diagnostics as reported by the OP are:
Click to expand...
So checking the gas port size is like an unnecessary medical procedure?
It shouldn't take more than 10 minutes to check it.
I sent my RRA Varmit back when it was new. Guess what? Wilson drilled an undersized gas port in the barrel and then RRA reinstalled the gas black canted.
A buddy of mine brought me his rifle because it wouldn't cycle at all. The replacement gas block had the gas port drilled on the wrong end. It was a manufacturer FUBAR.
Telling the OP what not to check after 70 posts of redundancy without prevail means it time to think outside the box.
OP - Didn't you say you replaced the BCG? If so you probably eliminated that as a cause.
 
Telling a newbie to drive the pins out of an A2 sight, on say a DD upper, to check the gas port (for example) would be....how shall I say it.....CRAZY.

My vote right now is start with the "simple" stuff first. But let's wait for the OP to jump back in, he may have solved the issue.
 
I wonder if the previous owner fired a bunch of .22 LR in it. That would indeed foul the gas block with lead. Pour a bunch of hoppies #9 down the gas tube and let it soak for a day. Get lonf pipe cleaners to run down the gas tube. If you know someone with a sonic cleaner have them drop in the bolt and carrier for a 30 min run in it. Then a bit of grease on the rings and some quality ammo and let us know if it works.
 
oldschool45 said:
I picked up an A2 style AR with a 20" barrel from a local pawn shop lets call it close to dirt cheap. I like the accuracy I got out of it but it didn't cycle. The shop gunsmith took a crack at it and replaced the BCG group with a Nickel Boron one. It no cycles but not 100% of the time. He says he got 15 rounds cycling fully.
I don't care to take it back again and its not going to be a home defense gun so perfect reliability isn't a concern.
Some thoughts; I'm using brand new 10 & 30 round Pmags. Would moving to a lighter buffer or spring help?
Thanks,
Click to expand...
Has anyone suggested replacing the gas tube?

Be easier and less likely to bugger up than pulling the FSB.

Maybe the previous owner didn't hear MistWolf's advice about pipe cleaners....
 
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