How should I handle surface rust on my rifle barrel or underlugs? Remove the barrel from the stock and scrub the rusted areas with oil and fine steel wool. Topics: Building & FinishingLast verified: 2026-08-16Also called: iron nitrate, iron-nitrate, aqua fortis, aquafortis, nitric acid stain, ferric nitrate, under lug, underlug, under-lug, under lugs, underlugs, draw loop, draw loops, barrel, stock, wood, woodwork, stock blank