Trying to diagnose a potential gas issue

[Drifter]

Anyone know what size hole should a 18in barrel have for a rifle length gas system?

~0.095" + or - 0.002" dependent upon other variables (ammo, buffer weight, buffer spring length & strength, BCG weight, etc).

An 18" w/ RLGS can be finicky when port size is down around 0.091"

[NugginFutz]

~0.095" + or - 0.002" dependent upon other variables (ammo, buffer weight, buffer spring length & weight, BCG weight, etc).

An 18" w/ RLGS can be finicky when port size is down around 0.091"

+1 on the potential for being finicky. That combo is one of the most finicky, due to dwell time being so short.

But then again, XC, you wouldn't be asking about gas port sizes if you didn't already suspect this.