Dean I have a cousin to your J&T 16 6.5 Grendel that is over gassed. My 16 6.5 Grendel is the heavy profile CMV barrel with Phantom flash hider I bought it as a complete upper from J&T. I went a different route to solve my over gas issue. I bought a 12 Group Buy Green Mountain 1:7.5 twist barrel where I wanted to assemble an upper. Since I already had a Monster bolt I needed a bolt carrier. I decided to buy a Rubber City Armory adjustable gas key and a new stripped M-16 phosphate carrier, FP, FP retainer and cam pin. I moved the J&T bolt, cam pin, FP with retainer to the new bolt carrier with RCA adjustable gas key. I used my J&T carrier with my new 12 Monster barrel build.
The RCA adjustable key took care of my J&Ts gas issue as it now ejects brass to 3-4 O Clock. Even Wolf steel case was ejected at 2 O clock without adjusting the gas on the J&T. I was using an H2 buffer with the J&T upper so I just left it in there and adjusted the gas. This has really improved the functioning of this 6.5 Grendel. I never measured my gas port on my 16 CMV barrel but it never lacked for gas! This J&T barrel shoots really well and Im glad I decided to try the RCA adjustable carrier.
The RCA adjustable key took care of my J&Ts gas issue as it now ejects brass to 3-4 O Clock. Even Wolf steel case was ejected at 2 O clock without adjusting the gas on the J&T. I was using an H2 buffer with the J&T upper so I just left it in there and adjusted the gas. This has really improved the functioning of this 6.5 Grendel. I never measured my gas port on my 16 CMV barrel but it never lacked for gas! This J&T barrel shoots really well and Im glad I decided to try the RCA adjustable carrier.