Failure to feed

[mike1]

I have an AA 14.5" upper that intermittently (25% of the time) fails to feed. The symptoms are a round stuck at 45 degrees with tip of the bullet in the receiver extension. The cartridge case has a couple of indentations just bellow the shoulder which I'm assuming are caused by the bolt. The upper is a factory AA unit. I've tried multiple magazines (AA 10 rounds, CProducts 25). 2 lowers with H2 buffers. I'm pretty sure i tried an H buffer at sometime as well. Wolf MPT and Hornady A-MAX ammo. The bolt locks back on a single round. I would say the problem lies with the upper. I looked in the chamber and nothing stands out. The hardware is a couple years old. I had problems so I shelved it. I recently tried using it again.

Any ideas as to what's wrong?

[stokesrj]

I would say it is the magazine feed lips. I've seen several with the lips adjusted to point the bullet to low, tweaking the feed lips so the bullet was pointed at the feed ramp solved the problem pronto.
Bob

[LRRPF52]

Welcome. What ammo are you using? If it's the Wolf 123gr SP, that will do it. Try Hornady 123gr AMAX, or Wolf 120gr MPT.

Does the bullet tip get stuck in the breech, without making it into the chamber? I would also look at the ejector if the ammo isn't Wolf 123gr SP. If you radius the edge of the ejector, it will allow the cartridge head to slip into the bolt face. If a sharp ejector face is present, it can hang up the head of the case, and cause the exact malfunction you describe.

Since you tried different lowers, and different mags, I'm leaning to the ejector as the culprit.

[mike1]

I've been lurking a little lately and I was also on the old forum. I've used Wolf MPT and Hornady AMAX. I'm pretty sure the nose of the bullet is stuck in the breech given the cartridge's 45 degree to horizontal orientation. I found the thread on the ejector caused FTF. My symptoms are not exactly as picture in that thread but a long ejector is the most likely culprit at this time.

Welcome. What ammo are you using? If it's the Wolf 123gr SP, that will do it. Try Hornady 123gr AMAX, or Wolf 120gr MPT.

Does the bullet tip get stuck in the breech, without making it into the chamber? I would also look at the ejector if the ammo isn't Wolf 123gr SP. If you radius the edge of the ejector, it will allow the cartridge head to slip into the bolt face. If a sharp ejector face is present, it can hang up the head of the case, and cause the exact malfunction you describe.

Since you tried different lowers, and different mags, I'm leaning to the ejector as the culprit.