AR-10T not cycling, please help

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9 years 11 months ago #44007 by SubaruEJ25
AR-10T not cycling, please help was created by SubaruEJ25
Hey guys I'm new to the world of AR-10s but a long time shooter. I recently purchased an Armalite AR-10T, it was manufactured in 2007 but appears to be a safe queen. It has a lot of nice upgrades; Vtac rail, JP muzzle brake, JP gas block... Anyway, I take it to the range and after the 1st few rounds it stopped cycling properly. It would either fire and eject without reloading or jam a round half way in and dent the case. I am using 168 gr PPU match bthp's which have been very successful in all my .308 bolt guns. I tried using liberal amounts of CLP on the BCG and adjusting the gas block but still have cycling problems. Can anyone offer some advice? Thanks!!!

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9 years 11 months ago #44009 by jtallen83
Replied by jtallen83 on topic AR-10T not cycling, please help
Any evidence of gas leaking at the block or between the tube and the BCG?
When you say adjusted the gas block what exactly do you mean? Sometimes they are a little out of position from the port.

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9 years 11 months ago #44010 by Siscowet
Replied by Siscowet on topic AR-10T not cycling, please help
I get nervous when I hear aftermarket gas block. That would be my first suspicion. Like JT says, I wonder if the gas block is a little out of alignment with the gas port in the barrel. Is the gas adjustment secure, or could it work itself partially open with repeated recoil? Doubt it is the ammo. It might be just break in. Lube it up and run some surplus ammo through it and see if it loosens up, otherwise, check with a competent gunsmith. Wonder if the previous owner has the original gas block?

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9 years 11 months ago #44013 by Libertarian623
Replied by Libertarian623 on topic AR-10T not cycling, please help
Maybe you could single load a couple of rounds , pay attention to the way they are ejecting, and make note of any dents to the brass or ejector marks. Pictures help a lot. Also tear it down and do a inspection of everything while your at it. As stated above it is probably a problem with the after market gas block, but it doesn't hurt to run through everything while your at it. You eluded to the fact that you are being liberal with the oil but to put it in simple terms , you could dip it in oil and I would only be happy at that point . When breaking in a AR10 seriously excessive lubing is needed. This gun may have never been fired you just don't know. Also don't expect a flawless first hundred rounds that hardly ever happens, but things should smooth out pretty quick. Remember communications is a two way street, we are interested in your observations and helping you out.

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9 years 11 months ago #44017 by SubaruEJ25
Replied by SubaruEJ25 on topic AR-10T not cycling, please help
Thanks for all the help. As for adjusting the gas block i meant turning the adjuster screw with an allen wrench. I did notice some carbon deposit where the gas tube and gas block meet, is that normal? I can not see any other signs of leaking. The adjuster screw has not been loctited yet since i am still making adjustments. It's snowing today so i can't make it out to the range, in the meantime i will tear it down and oil it up again. The block is on pretty tight so i was hoping to rule out some variables before i take it off.

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9 years 11 months ago #44019 by jtallen83
Replied by jtallen83 on topic AR-10T not cycling, please help
I usually see a small amount of carbon between the tube and gas block but that is after a good 40-60 rounds, keep an eye on it and see what you get.
I'd see if you can find adjustment directions for the gas block from JP. If it were me and I didn't have the directions I'd start wide open and turn it down till function issues start then back up a bit, down side to that is your tuning the gas to one specific load so if you want to shoot something different you'd have to start over.
Best of luck :usa:

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9 years 11 months ago #44025 by SubaruEJ25
Replied by SubaruEJ25 on topic AR-10T not cycling, please help
JP recommends closing the block, then backing off 2 full turns and opening it up in 1/2 turn increments til you get your desired results. The screw will not sit flush to the block but I do not think that is an issue, please correct me if I'm wrong. I have some cheap Colt/Barnaul 168 gr I can run through it for break-in. It should be closer than using 145/147 gr surplus. Although the PPU match isn't FGMM expensive, it still gets pricey throwing it down range for testing. It's going to be in the teens here in the North East so my testing might be a little limited. I will post some pics of anything interesting I run into over the next day or 2. Thanks again!

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9 years 11 months ago #44026 by SubaruEJ25
Replied by SubaruEJ25 on topic AR-10T not cycling, please help
My hands are greasier than a KFC dinner without napkins but the BCG and upper are slathered in CLP. When I charge the handle and pull the trigger (yes I know dry firing is a No-No) I get a silky, squishy bolt release. I hope I can work out all of the kinks and keep using the PPU match ammo. I have a ton of it an it groups very well in my other rifles.

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9 years 11 months ago - 9 years 11 months ago #44028 by Libertarian623
Replied by Libertarian623 on topic AR-10T not cycling, please help
Sounds like a plan, look forward to your successful report. PS I dry fire all the time.. literally thousands of times a year. Never had a problem.
Last edit: 9 years 11 months ago by Libertarian623.

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9 years 11 months ago #44029 by Siscowet
Replied by Siscowet on topic AR-10T not cycling, please help
One other thought: did the previous owner replace the original buffer tube? Most AR's are overgassed to ensure reliable cycling, just what yours sounds like it isn't doing. Also check the gas ring on the bolt. Does it have any visible flaws or breaks? A silky squishy bolt release? My two AR10's do anything but that. It is a very direct positive release when I press the release button.

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