New A1 failure to feed

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SIMODshooter
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Sun Sep 06, 2020 9:56 pm

I have four A1 14.5 uppers...

I zeroed the first one two weeks ago and had failure to feed on the left side feed ramp. It did the same thing as MAC/Tim had on his review. Pushed nose.of bullet in. I was using Troy Industries Battle mags.
And 55grain ball ammo.

Zeroing the other three next time out.

Curious if it is an issue with the poly mag.

Has anyone polished the feed ramps and cut them down slightly lower? It only happens on the left side feeding. I had four failures in 200rounds.

Other than the four gun one ran flawless. Strange to not have as much heat and gas from the chamber.

Thanks


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apex
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Mon Sep 07, 2020 2:04 pm

If it happens with a different mag it might be that the barrel extension was not timed correctly and the left feed ramp is off enough to cause an FTF.
What brand of ammo are you using?
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Arkane
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Mon Sep 07, 2020 10:10 pm

I have to ask - Tula ammo?
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SIMODshooter
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Tue Sep 08, 2020 9:22 pm

Federal white box 55grain... i did run a magazine of steel case with no issue.

Zero issues with the aluminum GI spec magazine I brought.

The tip was getting stuck literally right below the right side feed ramp. First time I cleared it and kept going. Second I actually looked at it close before clearing it. The last two same exact place.

Looked like if the feed ramp was tampered down slightly it would be fine.
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apex
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Thu Sep 10, 2020 8:18 pm

How large is the gap between the upper and the lower?
This is how a normal mag should sit- the tip of the dummy round is about 2mm higher than the bottom of the feed ramp.
IMG_0995.jpg
Outlined the tip of the dummy round for your convenience:
IMG_0996.jpg
This mag is a C-Product steel GI magazine.
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gg5k
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Sun Oct 04, 2020 9:36 am

i had this exact issue with a friend's 14.5 upper, was happening with my asc mags, never happened when using my lancers. would always be left side round regardless of m193 or reman stuff, a firm tap to the bottom of the mag would cause the round to jump up and feed, did have a couple where the round did get set back into the casing though, figured it's just a magazine issue, though interesting seeing this very exact hiccup described by someone else.
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SIMODshooter
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Mon Nov 02, 2020 6:07 pm

After watching MAC/Tim have the same failure with a mag I think it was the Troy Mags. I sold them.

Need to go back out and run all four guns to break them in and sight them again. I just added 45 degree back up sights to mine.
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schuang
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Tue Nov 03, 2020 10:58 am

Hi I am new to here. I have the similar feeding issue from time to time on my 12.5 upper. I suspect it is due to too fast of cycling speed using the regular buffer. I think because bolt closes too fast before magazine spring can feed the ammo in the chamber properly. I am going to try H2 buffer for the next few session and report back here.

Sean
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apex
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Fri Nov 06, 2020 4:58 pm

schuang wrote:
Tue Nov 03, 2020 10:58 am
Hi I am new to here. I have the similar feeding issue from time to time on my 12.5 upper. I suspect it is due to too fast of cycling speed using the regular buffer. I think because bolt closes too fast before magazine spring can feed the ammo in the chamber properly. I am going to try H2 buffer for the next few session and report back here.

Sean
What ammunition are you using? My 14.5 did the same thing with Wolf Poly 55gr FMJ, and needed a custom 7.5oz carbine buffer for it to cycle correctly. However, since I decided to switch to brass (thanks to current ammo situation @onion19@ ), Norma 55gr FMJ .223, Frontier 5.56 M193, and IWI M93 all cycled fine with just a 3oz buffer. I even threw in some KNS anti-rotation pins I had lying around from another build, and those would always cause so much friction on the bolt on the previous build that it would short stroke... but on the 14.5? Nope! Ran like a champ with the KNS pins + Norma + 3oz buffer + standard carbine spring.
@onion35@

Anyways, easiest solution is to throw in an H2 (actually H2s are widely recommended on piston ARs) and see what happens.
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schuang
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Fri Nov 06, 2020 10:36 pm

It is for sure ammo sensitive cause I am shooting with my own reload. I had a flawless few hundred runs with 55gr everglade bullet with 22gr H355 powder. As soon as I switched to Barnes HP 40gr with 26gr powder, the problem start showing up. I suspect it's over-gas with later load so heavier buffer should help as well.
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