Aero M5 BCG hitting RE

[grimmpdx]

Hey guys, new here. Trying to get something all sorted out and some correct information. Just built a 308 on an aero platform and noticed my BCG is beating the crap out of my RE. I think this is a fairly common problem, but I'm trying to find a real solution, not band aids. I'm not dropping quarters down the tube, a spring and heavier buffer wont fix it either. Something is too long, or something is too short. This has lead me to a few options: Slash's heavy buffer and spring, JP SCS, Vltor tube, Armalite spring with h3 buffer, or the option I just found.. Armalite Buffer Setup. This is $55. It's by far the cheapest option and as far as I can tell, it'll serve me right and fix my problem. Am I wrong or is this the same tube dimensionally as the Vltor one I keep reading about? I'd prefer to switch to an AR10 buffer system since the increased length just makes sense considering the 308 pressures. Let me know what you think..

My Rig:
Aero Upper
Aero Lower
Aero MLOK handguard
SAA buffer, tube, spring
Toolcraft NiB BCG
Faxon 18" Medium profile mid length gas barrel
Faxon gas block
VG6 Gamma brake
Magpul ACS

 

[mike_f]

I used this on Aero M5 build:

PATRIOT ORDNANCE FACTORY - AR-15/M16 ANTI-TILT MIL-SPEC BUFFER TUBE

ETA: A common problem with 308 AR builds is bolt carrier tilt similar to what happens sometimes with piston AR builds. Since the bottom of your buffer tube is what looks beat up the most, I think that is at least a big part of your problem. The POF buffer tube has lips that extend on the bottom to help prevent your bolt carrier from tilting down before it starts into the receiver extension/buffer tube. My Aero M5 build has a Faxon barrel, an Areo BCG & the POF anti-tilt; and I haven't had any problems.

 

[Velocity Chad]

The armalite buffer tube is longer than the dpms style that aero requires and uses an ar15 carbine buffer instead of the short buffer. If everything is truly in spec, the internal length when the spring is bottomed out will be the same. Your buffer should be just under 2.5" and 7" internal length on your tube. I bet one of the 2 is out of spec.

 

[eklarsen]

In the picture it appears that the BCG is hitting the tube before engaging the spring, do you have the tube screwed in correctly and is the spring being pushed off the pin when closing your upper?

Is you gas block adjustable? If so you need to turn down the gas a bit to slow the BCG down.

Take a pic to the side with the upper closing to show the spring engagement, but those are my best guess.