AR 10 FTE

[ExAgoradzo]

What are the common reasons for a FTE on an AR platform.

this is a brand new build. It is my first build.

I am using American Quality Ammo 308 168gr.

I am getting the ammo to group well enough, but it is essentially a single shot rifle. Very frustrating.

thanks,
Greg

 

[silicosys4]

We need parts info before anybody can help you figure out your problem. Most importantly, buffer, spring, BCG/bolt, barrel, and the gas system.

 

[ExAgoradzo]

It was a Aero Precision Kit I got from my LGS.

the Upper was a different manufacturer my LGS had on hand.

the stock is a Magpul MOE Rifle.

I don’t know all the details, If these photos don’t answer the questions then I will get that info.

 

[shoobe01]

I'll also ask: Failure to... What? Eject or Extract? What /exactly/ is happening when it stops, what does it take to clear the stoppage, and what's an ejected piece of brass look like?

So Aero is the... lower? But the upper is something else?

The kit should have come with some paperwork, check packaging if you kept it. If not a parts list there, then hopefully a model number/name and we can all look on the mfg website to see what the bits are.

 

[ExAgoradzo]

Failure to eject is my prob.

it loads fine then stove pipes or doesn’t even get that far.

I wondered if it could be week ammo.

The gas block I got doesn’t have an adjustment so...

I’ll look for the papers tomorrow.

Greg

 

[dcloco]

Is the gas block AND gas tube aligned with gas hole in barrel? Easy check - spray carb cleaner thru the tube from the chamber end.....should was out through the muzzle if clear.

Correct buffer and buffer spring for 308?

 

[MistWolf]

Did you perform a lockback check? That will tell you if your AR is short stroking.

 

[MySuomi]

As dcloco mentioned I would check the buffer and spring and make sure they are 308 ready.

 

[ExAgoradzo]

How do I ‘check the spring and buffer.

I bought them from a guy who builds ARs. What do I look for?

I will do the lockback and carb cleaner tests tonight: how do I check the buffer and spring?

Thanks Gus!

greg

 

[MrCleanOK]

Did you clean and dry the gun for the photos, or is that the condition you fired it in? If that's how you were trying to fire it, put some lube in there and try again. Machines with moving metal parts don't tend to like being bone dry.

 

[dcloco]

How do I ‘check the spring and buffer.

I bought them from a guy who builds ARs. What do I look for?

I will do the lockback and carb cleaner tests tonight: how do I check the buffer and spring?

Thanks Gus!

greg

Best info I have found. www.heavybuffers.com

http://www.heavybuffers.com/images/Buffer Table.jpg

 

[ExAgoradzo]

LUBE!

ok
I’ll google that!

good idea, thanks,
Greg

 

[ExAgoradzo]

So I watched a video.

what brand or lube do you use?

thanks,
Greg

 

[dcloco]

So I watched a video.

what brand or lube do you use?

thanks,
Greg

Oh dear Lord......the LUBE question. There is ten thousand available.

I prefer a 100% synthetic, light grease, with high temperature extremes. I use STOS.

In my experience, oil stays wet, collects dust/debris, runs where it wants, and needs to be reapplied as needed.

 

[Gordon]

I would guess miss aligned gas block or not the correct sized hole in barrel. The most common problem with ar10 builds is too much gas which causes double feeds and other problems, adjustable gas block is the answer. Also make sure your gas key is not loose in any manner as the pictures don't show much staking of it ! How does the bolt lock up ? when you hand feed cartridges thru the mag with charge handle CAREFULLY ! AND SAFELY , do they feed up ok and chamber ok ? When you let bolt release chamber a cartridge (CAREFULL) from the mag does it lock up tight and extract and eject ok ? In the buffer dept if you use the common type milspec carbine stock you have to have a special shorter length than Gi spec AR10 Carbine buffer and spring as the bolt comes back farther ! Those are the things I can think of. Also Your lower was made to take DPMS type uppers . I don't know if yours is of that type, and don't know what problems others cause. I know Armalite type won't work.

 

[ExAgoradzo]

The locking of the gun seems effective efficient enough. As I said, at the ignition stage there doesn’t seem to be a prob.

also the buffer spring was sold to me by a guy AFTER I told him I was using the rifle length Magpul stock.

I’ll get a synthetic lube. that has seemed the consensus to far.

I’ll report back as soon as I can shoot it: I don’t get to shoot very often because the range is an hour away. This is CA after all...
Greg

 

[MrCleanOK]

LUBE!

ok
I’ll google that!

good idea, thanks,
Greg

I think we've found our smoking gun. The simplest hypothesis is often the best one. I'd forget all about buffers, springs and gas blocks until you have a chance to go shoot this gun wet. What to use for lubricant is its own can of worms and I'm not going to get into it. Just use *something*. CLP, used motor oil, full synthetic, silicone bedroom lube, axle grease. Nearly anything will do while you're trying to troubleshoot why the gun won't work. I've even successfully used human saliva in a pinch as temporary make-it-work juice.

I've seen LOTS of AR-15/10s choke for being too dry. They don't choke on being too wet, it's a self-correcting (mess-making) issue the first trigger pull or two.

 

[ZGunner]

Had a problem with no ejection when I put together my Aero .308. Turns out I left the gas tube out on my last assembly before firing, because I’m an idiot. But, it looks like you have that covered.

 

[MistWolf]

With an empty mag inserted in the well, does the BCG lock back when you cycle the charging handle?

From your photos, it appears that your AR has a rifle buffer. Unless your AR has a shorter than normal 308 BCG, or a longer than normal RE, rifle buffer is too long.

 

[mjsdwash]

http://out-of-battery.com/ar10-vs-ar15-rifle-buffers/ just for refrence. Lube is not your problem, don't drive two hours to find that out. Lube comes into play when things get hot and dirty. A working 10 will cycle dry. Push the buffer in the tube, put the carrier in and make sure it goes until nearly all the round part is in the tube, and the bolt is well behind the bolt hold open. If it does not, its an interference issue, if it does, its a gas/ejector/extractor issue. Will it eject a spent case a few feet when hand cycled? If so its a gas issue. If not, its an ejector/extractor issie. If its a gas issue, take the gas block off, and check alignment. It looks alike a low profile, which means it could be slightly off. You may need a washer on the barrel shoulder. If the gas block is designed for a G.I. handguard endcap, it will not line up with the hole unless there is a washer or shim the same thickness as a handguard cap.

 

[458MinMag]

I assembled a large format AR in 7mm/08 several years ago, and I was getting stove piping too. It took a while to figure out. My gun would eject an empty case when cycling the action slowly, but I found that the case would be knocked back into the loading port if I yanked the BCG back rapidly. I took slow motion video on my iPhone and watched what was happening. The neck of the case was hitting the inside edge of the ejection port, just aft of the barrel extension. This would knock the case out of the extractor and it woudn't clear the port. I chamfered the inside edge with a long carbide burr in a Dremel tool, and it has worked great ever since. Something to check ...
Edited to add... I also stoned the corners of the extractor claw, and I'm running dual spring+o-ring under the extractor.

 

[ExAgoradzo]

Gents! Thanks!
I will go through all these on Saturday.
This is the kind of ‘check this...’ I was hoping for.

FTR: I’m getting FrogLube from Amazon.
I had to get something else too otherwise I would go to Midway.

thanks again,
Greg

 

[MarshallDodge]

Gents! Thanks!
I will go through all these on Saturday.
This is the kind of ‘check this...’ I was hoping for.

FTR: I’m getting FrogLube from Amazon.
I had to get something else too otherwise I would go to Midway.

thanks again,
Greg

Apply FrogLube very thin or it will gum up your action.

For testing purposes you can use regular motor oil. Some shooters swear by Mobil 1 synthetic.

 

[ExAgoradzo]

Thanks for the tip on Mobil1. Cheaper for sure... what weight?
Greg

 

[bearleft]

30 wt. has worked well for me!!