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10 years 5 months ago #39580 by mardad
Fail to feed was created by mardad
I have an AR10 that was born an A2. Bought an A4 stripped upper from a distinguished forum member here and just had it put together.
It fires, cycles , but does not chamber next round. It will eject and chamber perfect manually. Tried all of my Armalite mags. Same thing.
Checked earlier posts on this and sounds like it is a lube problem. Could the ramp need to be polished or could it be over gassed???
Thanks for any help.

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10 years 5 months ago #39581 by Ranchwagon
Replied by Ranchwagon on topic Fail to feed
I had the same issue. As near as I could tell, the gun just needed cycling because the manufacturing tolerances are tight from Armalite. I ended up lubing the crap out it (dripping almost) and once I put about a 100 rounds or so through it, it worked fine. I ended up lubing the magazines as well to resolve and intermittent feed problem (new mags).

Hope this helps.

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10 years 5 months ago #39582 by mardad
Replied by mardad on topic Fail to feed
Thanks Ranch. I'll give it a bath and "let it rain"

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10 years 5 months ago #39585 by jtallen83
Replied by jtallen83 on topic Fail to feed
What ammo are you using?

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10 years 5 months ago - 10 years 5 months ago #39589 by mardad
Replied by mardad on topic Fail to feed

jtallen83 wrote: What ammo are you using?


Lake City 149 and Win. American Eagle 150 FMJBT

Sorry guys. Just realized I put this in the new member intro. cat.
OOPS! :naughty:
Last edit: 10 years 5 months ago by mardad. Reason: wrong place

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10 years 5 months ago - 10 years 5 months ago #39590 by Siscowet
Replied by Siscowet on topic Fail to feed
Thinking if that doesn't work it might be the fit between your lower and upper not aligning the magazine correctly with the bolt. Try the lubing first. If that doesn't work, might check the tolerances between the upper and lower. Gaps, looseness, etc. for what ever it is not cycling the next round. Have you tried manually cycling it at the range, safely, of course, with some live rounds and watching the bolt and magazine interaction? Do they pick up the round? Try lubing first, then go from there. Also as JT inferred, the ammo might not be pushing the bolt far enough back. If you can cycle manually, but after firing, try different ammo. If it still happens, check your gas tube, is it fitting properly into the BCG? If after all this it doesn't work, have a gunsmith or Armalite check the size of the gas hole in the barrel and if it is properly lining up with the gas block. That could cause a reduced amount of gas impinging on the bolt. Try the easy stuff first.
Last edit: 10 years 5 months ago by Siscowet.

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10 years 5 months ago #39592 by mardad
Replied by mardad on topic Fail to feed
Thanks Sisco
I'm hoping the lube is the answer. I'm probably thinking basakwards..... but I was thinking I was getting too much gas on the bolt since I can cycle it perfect manually, 28 rounds , as fast as I can pull. No "scars" on the round following...... love this rifle, really want it to run. Gonna make it splash and see what happens.

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10 years 5 months ago - 10 years 5 months ago #39593 by Siscowet
Replied by Siscowet on topic Fail to feed
Over gassing wouldnt cause that as much as it would cause really violent extraction of the empty brass. What do they look like? AR's are intentionally overgassed somewhat to ensure extraction. Any excessive tear marks on the rim? I say excessive, because some are typical. Undergassing might be allowing the bolt to go far enough back to extract the empty case in the chamber, but not far enough to pick up another round off the magazine. If you can manually cycle, it is not alignment.was the barrel and gas block taken off the A2 and put on the A4 upper reciever? Or was it a complete upper barrel and all. If they were moved I am thinking maybe alignment of the gas block and barrel might not be centered.
One other thought: did you change buffers? If the buffer spring is too strong, it might again not allowing the BCG to cycle far enough back to pick up the next round.
Last edit: 10 years 5 months ago by Siscowet.

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10 years 5 months ago #39600 by NightForce
Replied by NightForce on topic Fail to feed
I have an AR-15 which exhibited the exact same symptoms.

I was shooting standard green tip 62 grain rounds.

Initially, I would rack the slide, chamber a round, and fire it. The bolt ejected the fired case but would not cycle back far enough to chamber the next round. The more I cycled and fired the rifle the better things got.

I also fired some hand-loads individually because the COAL exceeds the 2.260 magazine limitations. I used an empty magazine to lock the bolt back making it easier to cycle the bolt. These loads cycled the bolt back to engage the bolt catch every time so things are breaking in nicely...

I am running it dry so a little Mobil 1 in the upper would help a lot... :thumbs:

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10 years 5 months ago #39631 by mardad
Replied by mardad on topic Fail to feed

Siscowet wrote: Over gassing wouldnt cause that as much as it would cause really violent extraction of the empty brass. What do they look like? AR's are intentionally overgassed somewhat to ensure extraction. Any excessive tear marks on the rim? I say excessive, because some are typical. Undergassing might be allowing the bolt to go far enough back to extract the empty case in the chamber, but not far enough to pick up another round off the magazine. If you can manually cycle, it is not alignment.was the barrel and gas block taken off the A2 and put on the A4 upper reciever? Or was it a complete upper barrel and all. If they were moved I am thinking maybe alignment of the gas block and barrel might not be centered.
One other thought: did you change buffers? If the buffer spring is too strong, it might again not allowing the BCG to cycle far enough back to pick up the next round.


Good ?'s
No bad scars on extracted cases. No nose bleeds on the following rounds that don't chamber after firing.
The upper was a stripped A4, so yes, it could be the alignment.
I LEFT THE a2 STOCK AND BUFFER.
I'm still hoping it's break-in and lube.
If I run into a wall I'll be back.
Thanks again to all.

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