I have a CMMG upper. Put it on a PSA lower. I use the Redi-Mag adapter and the 15-22 mags.
The LRBHO is iffy on the Rdi-Mag once it gets dirty, so I changed to the AR Catch22:
https://arcatch22.com/ I had to use a Dremel to cut the Redi Mag LRBHO portion out of the Redi-mag adapter so it can fit, but that's easy and not a precise process at all.
I use a Tacom3G firing pin, buffer spring, CF handguard, and CF stock.
From Bore Buddy -
https://borebuddy.com/ I have replaced the extractor spring and use their adjustable bolt weight system replacing the CMMG plastic one which is too light.
I also added Hyperfire 24C trigger for extra hard primer strikes on some of those stubborn 22lr rounds and an Allchin muzzle brake to make the muzzle report louder so that shot timers can catch it better.
https://i.imgur.com/mXigrTI.jpg