Does anyone know the gas port sizing on PSAs CHF Nitride 14.7 mid length gas barrels?

Im using a BCM Intermediate Buffer System (A5) Kit  be with a Vltor A5H0 Buffer (3.8oz), While this combination works its seems to me that the gun is over gassed. If I know the gas port size on the barrel I could probably get the correct buffer weight.

If someone could tell me what buffer weight they are having success with on a standard carbine buffer tube I could work with that also.

http://palmettostatearmory.com/psa-14-7-midlength-a2-chf-5-56-nato-1-7-nitride-barrel-assembly-516444648.html

nobody knows?