Update on my Brownells Colt 6960 CCU upper. I finally shot it twice in the past couple of weeks, first on a 6920-R Trooper lower and then (as pictured) on my CM762 lower via the conversion block. Blue Springco and H2 buffer in both cases. Only 60 rds total so not a lot of rounds through it but still fun to get it out and vetted a little bit.
I did swap out the Centurion rail it came with for the one on the 6920-R Trooper - Since I use the Colt Trooper more, I wanted the integral QD sockets machined into the rail for it and put the simpler Centurion rail on the 6960 CCU upper. Paired the CCU with a Toolcraft BCG and Geissele ACH, along with a Aimpoint Pro / 3X-C.
It shoots great, after zero I was banging steel at 100 with ease with the RDS, both with / without the 3X in use. I got another MBUS Pro rear today (KY Gun CO had them for $65 each recently so I'm outta the plastic sight business
) to complete the upper and it'll probably live an easy life as a spare rifle upper for the CM762 or other lowers I have laying around.