Here's an example of Evergreen blast-tubes on my Monogram F4F WIP:
A little Steel paint, then a tiny drop of black wash for depth, and yer done... Also, it works well for adding the angled, muzzle-end blast-tubes seen on B-26 and B-17 tailguns, as well as B-17 chin-turrets.
(BTW.... Nothing wrong with your monitor's color-management... That's a US Navy CPO/pilot I'm painting there... I'm trying to depict one of the "Flying Chiefs of Fighting Two" (VF-2 "Rippers") from the U.S.S. Lexington... Not enough "contrast" between the summer flightsuits and a Chief's Khaki uniform, so I'm employing a bit of artistic license with the dungarees...