Aero M5 Ar10 build gas issues

[omenwolf]

So I built an Aero M5 Ar10 18" with rifle length gas system. All Aero parts including aeros .750 adj gas block. Its perfectly strait as well, I blocked the chamber and put air compressor on the tube and there is tons of air movement, I have the gas block set to full open with in their paper work is 15 clicks but it goes a few after that. When I got the aero buffer kit it came with carbine weight buffer. When shooting the bolt will not lock open and some ammo would short stroke. I am also running a silencerco 3 port ASR brake for when my can is out of jail. So I'm wondering is the comp robbing some of the gas for reliable cycling and or is the carbine buffer to heavy for a rifle length gas system? I know AR10s can be fussy so any experienced help would be greatly appreciated. Probably shouldn't have rockset the brake on before testing but got all caught up in the build and wasn't thinking.

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[msgriff]

How many rounds down range? They do have a break-in period and the BCG should be ran very wet during that time (no grease). Make sure that the barrel and extension are thoroughly clean. Do the standard function check of manual BCG travel and check the distance between the bolt face and bolt catch at full pull back of the CH ( l like 0.150" - 0.200"). Load one round in the mag and shoot to check bolt hold open. Check the condition of the brass for lug scrapes, extractor swipes and ejector divots.
I run similar, but not in your exact configuration, Aero set-ups and here are some of my opinions:
Over-gassed/overspeed is often confused with under-gassed, so don't discount either.
Aero uses 3.8oz carbine buffers. I feel that contributes to a over-speed condition which can cause the BCG to fly over the bolt catch and cartridge. It might be solved by turning down the gas, but i use a heavier buffer (5.6oz) in addition to a AGB to solve that problem. One downside to heavier buffers is an increased chance of broken bolt catches, especially with excessive distance between the bolt face and bolt catch. Earlier Aero bolt catches did have some breakage issues, but I've not heard of any lately. I am unaware of anyone using a lighter buffer than 3.6oz
I run a 18" BA barrel w/rifle gas and a aggressive brake and the brake does not affect cycling. The gas port on that barrel is 0.089", which is probably the same as yours. That barrel, however, is on a build using a rifle length action system. My carbine length actions are on builds with 16" barrels and mid length gas, also with brakes, and no issues.

 

[omenwolf]

How many rounds down range? They do have a break-in period and the BCG should be ran very wet during that time (no grease). Make sure that the barrel and extension are thoroughly clean. Do the standard function check of manual BCG travel and check the distance between the bolt face and bolt catch at full pull back of the CH ( l like 0.150" - 0.200"). Load one round in the mag and shoot to check bolt hold open. Check the condition of the brass for lug scrapes, extractor swipes and ejector divots.
I run similar, but not in your exact configuration, Aero set-ups and here are some of my opinions:
Over-gassed/overspeed is often confused with under-gassed, so don't discount either.
Aero uses 3.8oz carbine buffers. I feel that contributes to a over-speed condition which can cause the BCG to fly over the bolt catch and cartridge. It might be solved by turning down the gas, but i use a heavier buffer (5.6oz) in addition to a AGB to solve that problem. One downside to heavier buffers is an increased chance of broken bolt catches, especially with excessive distance between the bolt face and bolt catch. Earlier Aero bolt catches did have some breakage issues, but I've not heard of any lately. I am unaware of anyone using a lighter buffer than 3.6oz
I run a 18" BA barrel w/rifle gas and a aggressive brake and the brake does not affect cycling. The gas port on that barrel is 0.089", which is probably the same as yours. That barrel, however, is on a build using a rifle length action system. My carbine length actions are on builds with 16" barrels and mid length gas, also with brakes, and no issues.

I am also running the BAD lever style phase 5 bolt catch. I got about 125rds down range. Bolt was wet but just a thin coat rubbed on with my finger. I didn't check the brass but didn't notice anything out of the ordinary when I was cleaning up the brass. It was short stroking and bolt was getting caught in the middle of the round half in chamber and partly in mag.

 

[msgriff]

I have no experience with battery assist levers, so I can't help you there. I know they say that they're compatible with the Aero, but as a fallback, you may want to consider using the Aero bolt catch. You may have two separate issues to solve. You definitely have plenty of rounds through it and the lube might be adequate. Which brand of mags are you using? Have you tried to adjust the gas down, and if so, do you have the same FTF issue?

 

[omenwolf]

I have no experience with battery assist levers, so I can't help you there. I know they say that they're compatible with the Aero, but as a fallback, you may want to consider using the Aero bolt catch. You may have two separate issues to solve. You definitely have plenty of rounds through it and the lube might be adequate. Which brand of mags are you using? Have you tried to adjust the gas down, and if so, do you have the same FTF issue?

The bad lever is very balanced and the magpul mag push it up easily. I will try lowering the gas down next time out. Biggest culprit was the Winchester white box m80. Seemed the lowest power out of the magtec green box, pmc bronze, pmc xtac and federal red box. Might have just been break in. If It keeps not locking back I'll go back to the stock bolt catch. Just wanting to get it running reliably. I know a lot of people have issues with these ar10 builds and even worse when they add a can.

 

[Ridge Walker]

The bad lever is very balanced and the magpul mag push it up easily. I will try lowering the gas down next time out. Biggest culprit was the Winchester white box m80. Seemed the lowest power out of the magtec green box, pmc bronze, pmc xtac and federal red box. Might have just been break in. If It keeps not locking back I'll go back to the stock bolt catch. Just wanting to get it running reliably. I know a lot of people have issues with these ar10 builds and even worse when they add a can.

Have BADs on 2 Aero M4Es with Magpuls (and all other mags used so far) without issue.

 

[bfoosh006]

Fully close the gas block, so no gas flows.

Load and feed a single , mag fed round... adjusting the GB open until the bolt locks back from one of those single mag fed rounds.

Then try a few mag fed loaded rounds in the mag. The extra mag loaded rounds will add "drag" .. so don't be surprised if you need another click open.

Let us know if that helps. I am hesitant to suggest heavier buffers or a heavier recoil spring... mostly because of the RLGS.
My 18" 308/6.5CM are Mid-length gas.

But... if you do end up "needing" a heavier 2.5" buffer, Midway sells a 5.6oz KAK version>
https://www.midwayusa.com/product/1021956650?pid=724762