I have a Micro MOA 12.5” midlength. It came with a .089 gas port and I ran a govnah on it drilled to .049 / .052 for suppressed with a YHM ULT. I am using a JP SCS with the weakest spring, some of the weights removed, POF cam follower, LMOS bolt carrier, and Hiperfire 24C. In other words, the whole system is low friction and takes almost no gas to run. My problems have been inconsistency with the short dwell time/different ammo plus it gets INSANELY dirty fast with Freedom Munitions and even M193.

To counter the excessive dirt and dwell time/ammo pickiness I bought a Superlative Arms piston kit. However, it runs overgassed in bleed off mode I am not sure I got the screw all the way out as it was dark, but I was out like 7 turns. In restriction mode, it runs at only one click from closed. I suspect the 0.089” port is too big for the piston kit. The Govnah did at least choke things back well. I have not tried firing with the piston kit and no suppressor yet. I was out of daylight last weekend and had a 3 hour trip home.

From gas port to crown is about 2.7” now. I could probably chop the threads off and just make a new set of threads and make it an 11.8” barrel via ADCO or any other barrel turner/chopper. That should still leave me enough room for an allen wrench to barely access the gas screw behind the suppressor mount.

11.8” barrel would be 2.0” dwell compared to 2.7” dwell now (26% less gas).

Thoughts? This barrel has been a solid 2 moa shooter with cheap ammo and holds the suppressor weight well. Its 1.25 moa @ 100 yards with good ammo. I would like to get it working rather than replace it and go piston for a cleaner SBR/Suppressor combo. If S.A. would make a smaller piston and a sleeve/spacer I could just swap rods and install that, but I doubt they have any interest in my plight to that extent. That would also take a new op rod spring of a smaller OD.

Also, if it is overgassed even in full bleed off this weekend, I could chop saw 0.3” off the threads and still fire a few rounds with the suppressor to see the change. I could even then drill the end of the bore out with a 3/8” dril bit to about 12” barrel length. ALL THIS ASSUMES ADCO COULD TAKE MY HACK WORK AND STILL TURN A 11.8” BARREL WITH THREADS AND PROPER CROWN

Put down whatever you're drinking and step away from the workbench...
Throw a heavy buffer or standard carrier in there and see if that tones it down.  The Superlative Arms kit was intended for reliability with mil-spec or similar setups, not super low bolt mass builds.

Also, Freedom Munitions is nasty crap ammo.  You'd be much better off with Wolf Gold for cheap brass ammo.

I bought a few hundred pounds of freedom munitions during the Hillary scare.  I'm stuck with it.

Also this build is a game Gun.  No intention of going mil spec. I need lightweight parts and direct impingement was too dirty.

What's wrong with getting adco to chop it down if it's still overgassed?

I was referring to your suggestion to chopsaw and back-drill your muzzle then fire it through a suppressor...
Nothing wrong with having a barrel shortened and rethread/recrowned the right way.

Well the superlative piston opens up to 13 turns but still ran a little peppy.  Heavier buffer and spring helped but either way was......okay.  

With no suppressor it ran softer than a gas gun at 8 turns out.  I don't know if it's worth it to chop off an inch of barrel or not.  Would be nice to have suppressed running as smooth and soft as unsuppressd.

Well I had ADCO chop the barrel to 11.9".  I should have had them go all the way back to 11.5", but than it would have been hard to access the gas screw as it would have been just behind the YHM QD mount.  

Now unsuppressed runs at 7 turns out instead of 8.  The brass lands at about 3 or 4 oclock and about 6 or 8 feet away.  

Suppressed with the screw COMPLETELY open it still kicks a little and throws the brass to 2 or 3 oclock about 10 feet away.  its better than it was, but this barrel just has too big of a gas port.  I forgot to try restrictive mode with the suppressor , but I will in a few weeks.  

Right now I plan to just order some intentionally underpowered ammo for suppressed in this gun.  That should also make it softer shooting and more quiet.

If I get the nerve to start over, I'll order a 16" middy and chop it back to 12".  I can always drill a gas port if needed.  Not too many ways to make them smaller though.