When my wife & I, hydro-dipped her AR-15, we went to the trouble of dipping the upper & lower together. They were masked & painted separately for the base coats. The dip paint doesn't flow between the two sections when pinned together. I'm going to build another .223/556 AR, and dip it some camouflage, or maybe those "skulls". Might dip the upper & lower, and paint the handguard. I'm now past my mid 60's and I like that stuff! Hadn't even looked much at ARs until a couple of years ago.