Just finished it today.  12.5 middy. Jp scs. Hiperfire 24c. Pof roller campaign.  EDIT YHM ULT 30cal suppressor too.

It stayed overgassed in bleed off until the screw nearly backed out. I cut the gas off and it was off. Opened up one click and it runs.   What gives?  ONE CLICK OPEN RUNS!

Now this is a Micro MOA barrel.  It came with a EDIT 0.089" gas port, but I ran a Govnah on it drilled to .049" for suppressed.  If I have to turn the SA down so much to run I would guess I will get screw erosion.  I have not fired it unsuppressed yet and it will be next weekend before I get the chance.  

Also, how many turns out is full bypass with the SA piston system?

So if my barrel is too overgassed for the SA piston to run in bleed off, should I consider cutting the 12.5 back to 11.5?

Just curious, but what over-gassing symptoms have you identified?

Well now that I read my own post I sound like I am over reacting.  What I call overgassed is really about like a mil spec type gun.  I have had this gun set up for games in the past and in that condition it barely moves when fired.  The gun is probably fine at 1 click out and I have discovered I have more bleed off mode left to play with.

Closed - gun did not move much...duhh... but no cycle.
1 click open (restriction mode)  The gun ran just fine and felt pretty normal, but again only 1 click open cant be good for the gas screw.

4.5 turns open - full gas - the gun bucked and jumped when fired.  Brass shot to the next section of land lol.  Anyone could tell this was a violent cycle.

I kept opening until 8 turns out.  The screw looked like it was bout to come out of the gas block. This was done in near pitch dark by light of a cellphone.  The gun was bucking up a bit.  About like a milspec type gun.  I could tell it was not acting smooth like it did when I ran it with a tuned Govnah gas block.

Now last night I got it out and played with it at a table under light.  I got 4 more turns out in bleed off before the screw stopped clicking. SO I HAVE NOT GONE TO FULL BLEED OFF YET.  I was just afraid the screw would come out in the dark and land in grass last weekend.  So 12 turns out for clicking and a 13th turn with no clicking before the screw hit a stop.

In all likelihood, this weekend might just mean tuning the gas block then a full retraction here.

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.

You may have better luck just running it in restrictive mode instead of bleed-off mode. I started playing with mine last night, started at fully closed and worked it out to just one click after it fully locks back (9 clicks/2.25 turns for me). Will be playing around with it a little bit more when I get the go-ahead on my suppressor.

In restrictive mode with the suppressor it ran on ONE click from closed. That can't be good for the gas screw

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.

Interesting that removing just .6" of a barrel/dwell time has that much of an effect on your gas pressure, especially for it being a MicroMOA barrel.