Paired up nicely with an Aero M5 lower. Installed an adjustable gas block, the factory gas block is loctited in pretty good and took some doing to remove. Also added a GoGunUSA Supercomp XL and an Indian Creek Designs Blast Forwarding Device (BFD XL) that threads over the compensator. Heavy, solid, well-built complete upper receiver. Using a Brownells nitride BCG and Aero Breech charging handle. Can’t wait to get it to the range.