Aero M5E1 Feed Issues

[sbgixxer]

I put together an Aero M5E1 (my first .308 AR) and it looks amazing. I took it to the range a week ago to get it sighted in and after a few rounds, it stopped feeding. It was firing fine and ejecting spent casings like it should be had some trouble racking the next round. From my AR15 experience, I concluded that the issue is either the feed ramps or spring weight. I bought the upper finished so I would've figured the ramps would be good but the spring was part of a kit so I'd think the same there too. I've heard that these usually don't go together and function from the get-go quite as well as AR15s but my whole set-up is Aero. Hopefully some of you more experienced .308 guys can help. I'm including a few pictures of the feed ramps.... are they too rough?

76243 76244

[henpecked]

Check the front gas block, I saw one come loose just this past summer.

[Eric P]

I had the same problem after I swapped the gas block for an adjustable one.

All worked but every few rounds would fail to feed. Undergassed.

But this was on a PSA upper & lower. By the way the PSA upper doesnt fit the aero precision lower.

[sbgixxer]

What would I be checking, tightness? I don't have an adjustable gas block....maybe a worthwhile mod? So nobody seemed horrified by the feed ramps. They're as expected?

[KS63]

I’ll check mine when I get home, but I have a Faxon barrel.

[DireWolf]

What would I be checking, tightness? I don't have an adjustable gas block....maybe a worthwhile mod? So nobody seemed horrified by the feed ramps. They're as expected?Check the gas block refers in this case to making sure it didn't rotate or move (so as to no longer be properly aligned with the port on barrel). Worth checking.

Also, (failure description is a bit vague, so possible this may not be relevant) check to make sure your firing pin isn't bent and the bolt freely cams in the carrier, and that you're getting good contact between gas tube and gas key...

ETA: from what I can see in pic, would guess that your feed ramps are likely unrelated to the stated failure mode...

[sbgixxer]

The failure only relates to feeding the follow up round once fired... as in bolt open, mag in = feeds just fine, once firing it struggles to feed rounds. Now that I say that, it makes me think a gas issue since it never failed to chamber the first round. So not enough gas or too weak of rounds?

[henpecked]

Google shows 420,000 hits when typing in "Aero M5E1 failure to feed".
Other possible options are spring or buffer to long not letting bcg go all the way back.

[DireWolf]

Misaligned gas block/tube is a potential direct cause of insufficient gas.

Does the bolt "stick" close? e.g. - does it have to be "mortared" open, or does it eject the spent case normally? If it's sticking closed, pull the bcg, check the FP and make sure bolt cams smoothly...

If it does eject, how strong is the ejection? Subsequent to firing, does the bolt/carrier come to rest fully closed but with an empty chamber?
If so (and bcg checks out) then next thing I'd check (assuming good factory ammo in use, not crap/reman, etc.) is to make sure gas system components are aligned and unobstructed - start by check for block alignment, possible debris in tube, etc...Could be other issues as well (e.g. out of spec port, bbl, etc.) but those may take more effort to verify than the initial troubleshooting steps previously indicated.

ETA: from description it appears you're seeing full range of motion from the bcg, but good idea to verify that as others have mentioned...

Also, check to make sure you accounted for proper offset when mounting the gas block.

[Eric P]

A simple gas system check is to put one round in the mag. Fire it and see if the bolt holds open. If it doesn't, it's under gassed.

[sbgixxer]

Direwolf - The bolt doesn't stick closed, it feels smooth and operates as I'm used to. The failure either has the bolt closed with no round or the next round jammed between the mag and chamber. I'm going to try some different quality factory rounds to make sure what I was firing wasn't underpowered. With this forums help, I'm leaning towards the bolt not retracting all the way which either means lack of gas or too strong a spring.

Eric P - That's a good suggestion, I'll give that a try next time I'm out.

Thanks for all the help, fellas! [Beer]

[CobaltSkink]

C. Or too heavy of a buffer?

[FireMoth]

If its all Aero, odds are VERY good its running too fast, not too slow.
.308 tubb flat-wire spring, A5 style extension if carbine type stock to allow H2 buffer.
And possible chamber correction depending on what barrel.
A lot of the barrels have tight throats meant to help out the low pressure 147grn spire point bullet of the M80 ball round. Commercial .308 and Mil Match (MK118lr and clones) are much hotter with an ogive that typically will be hitting the lands on chambering.

Film your bolt travel on high speed, and watch your ejection pattern. Casings going far forward or erratically spinning off all directions would indicate too fast. If it was actually too slow, youd see ejected casings land close, at the 4 o'clock or farther rear

[SA Friday]

Or just bring it into the shop (Bowers Tactical) and let Firemoth or I take a look at it.

AR10's are fickle creatures with totally different temperaments than an AR15. Unfortunately the ease of setting up AR15s lulls many into the belief that AR10s will be the same. They are just the opposite. The slo-mo video is golden stuff to diagnose what's going on though.