i did this not long ago

18" BA match 223 wyle mk12 profile rifle gas - with 77 federal otm im at 1/2 MOA 100 yards

BCM blem upper reciever

BCM CH

Toolcraft BCG

Geislle MK8 13.5 rail

I want to say around $650 total for upper

I have it on a spikes lower with colt A2 stock kit, MBT larue match trigger and spikes Lower parts kit very soft shooting