Ar15 feeding problem diagnosis

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AnthonySmithXR

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I'm wondering if the brain trust can help me. I've got a 556 AR that I built (good parts and good assembly, I'm 99% sure of that). It's a Daniel defense 16"mid barrel. Carbine buffer.

I'm using a mix of usgi mags (foliage followers) and pmags (gray followers).

I put about 400 rounds down range today (that makes about 450 total in the guns life). Whatever mag I used I had intermittent feeding problems (mostly extraction and double feed). When I say intermittent I mean I could fire off 20 rapidly no problem, the switch to slow fire and have an issue every 2-5 rounds. Then nothing for another 20 rounds of slow fire.

The ammo was hand loaded xm193. Also, the gun was plenty well lubed and clean (it's practically brand new!)

I know there are a thousand things that could be the issue here, not least of which is ammo. Next trip to the range I'm going to eliminate that variable by using high-quality factory ammo. Now, assuming the problem persists, what might some causes and solutions be? The two things that come first in my mind are, number one, a slightly larger gas port. Or, number two, a heavier weight buffer.

Any other ideas? Am I on the right track? I would prefer to look at part swaps over modifying the barrel at this point. I'm willing to do it and I know that it's a normal thing. However I would like to leave that as a last resort if possible. Thanks a lot.
 
Yes, i would swap out parts before drilling out the gas port.

Try a heavier buffer and maybe insure the gas block and barrel prot are properly lined up.

You mentioned using two different magazines, have you identified whether it might be one of the styles or magazines that causes problems?

I have assemble 11 or 12 AR-15s without any issues until the last one I assembled. It has taken a while for the bolt carrier group to work itself in and I have had to lubricate it at the range just before firing. It is getting better and more trouble free as I put more rounds through it.

Hope this helps.
 
Failure to extract can be caused by too violent of extraction. Unless you can drill the gas port smaller I'd leave that alone.

1st: Try factory ammo.
2nd: Replace in order-
a) Extractor spring. I use Wolff extra power springs.
b) Extractor.
3rd: Add o-ring to extractor.

BSW
 
I have a ddm4v5 mid length. It is a factory build with an h buffer. Try that first and see what happens.
 
It's feeding two live rounds or one live one spent, which would be failure to extract? If you're have double feeds and failures to extract you have all sorts of problems.
 
Sorry. Auto correct and voice to text are screwing me up!

The specific issue I'm having is a spent round in the chamber and a live round shoved in behind it. Occasionally the bolt would be stuck hard and the case would come out with deep gashes (idk if from feed ramp or locking lugs.). I've ordered a new extractor set and will move from there.
 
OK much better..most likely it's the extractor spring. However on the fired brass that came out fine you need to check for any "rings" or scratches in it. It's possible the chamber could be part of the problem as well.

Is this a chrome lined barrel?
 
Double feed would be two fresh rounds trying to chamber at the same time. From your followup description you most definately have extraction issues.

Easiest to test first: use fresh full power factory ammo such as lake city 5.56 or equivalent, but not wolf ammo. Maybe your reloads are out of spec or the brass is swelled. Also check the chamber for any burrs or marks that might cause drag.

Next, replace the extractor spring and oring.

If you still have problems, the rifle may be over gassed, meaning that too much gas pressure is getting to the bcg too soon and forcing extraction before the chamber pressures have had time to drop. This could be caused by an oversized gas port for the length of the gas system. A heavier buffer could mask some of this, making the bcg recoil slower. Ideal fix would be matching the barrel gas port to the gas length, or use an adjustable gas block.
 
My ar, colt, never has a hickup until I load the rounds a little stiff. Gun lets me know that its to much. Back off powder a bit and runs like a deere.
 
Heavier buffer spring and new extractor spring with the o-ring is what I would try. So what if it is a Daniel defense upper the chamber could be rough causing the problem
 
Do you know anyone with an ar that will let you use their lower. If the problem stays its in the upper if it goes away its in the lower.
 
G.barnes said:
Do you know anyone with an ar that will let you use their lower. If the problem stays its in the upper if it goes away its in the lower.
Click to expand...
It probably isn't the lower but that is a good idea to find out if it is the lower
 
Who's bolt carrier group are you using and which weight did you go with on the recoil buffer?
The extractor kits might fix your problem. I haven't had the need for one so I haven't used one. For normal semi-auto shooting you shouldn't need it.
 
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