I have an UU 6.5G on order and I plan to have ADCO cut it down to 14.5 and P&W a Rugged Suppressors MB or FH onto it and I am wondering if I might need to go ahead and have the gas port opened slightly? The rifle will be shot suppressed 100% of the time and my Rugged Razor does create quit a bit of back pressure. Just curious if anyone has attempted this and if they were successful. Thanks in advance.

Whatever you do, I recommend getting the Bootleg Adjustable Gas Carrier so you can dial down your gas through the ejection port easily.

I used that for my last two 12" Grendel builds with TBAC suppressors.

Or you can just cut to 13.7" and P&W the LaRue Tranquilo and use the LaRue Tranquilo suppressor, which is a flow-through design that doesn't create back pressure issues.

Since you're cutting an 18" MLGS barrel down to 14.5" and adding a suppressor, I would leave the gas port alone.

18" MLGS is already gassed pretty hard with the ideal .076" port, and adding the suppressor will be like replacing the barrel length anyway.

16" MLGS Grendels also run best with a .076" port, so you'll be fine if you use the current gas port and don't mess with it.

I used the bootleg on my original 12.5 I had as well and it functioned perfectly. Regret selling it but this time I’ll do a complete LaRue instead of just the upper. Also thank you for the info as I was hoping you would step in and let me know since you are the go to guy on 6.5G around here. Now it’s just to wait on it to ship.

I had mine cut down to 16 inches and didn’t touch the gas system.  Runs perfectly.