Twelve 12 3-in.70 AA Projectiles Type Ex 24 Mod 9 were fired for recovery in the 3-in.70 gun Type G Mod 9 No. 24581. The subject gun, although having been fired only 554 equivalent service rounds, was in a badly worn condition due to spiral wear. The worn barrel was oiled with Navy Symbol 5190 oil to determine the effect on the rotating bands and the spin rate of the 3-in. 70 AA Projectiles. The firing was conducted in groups of three rounds each, the bore of the gun being oiled prior to the firing of the first round of each group. It is concluded that the presence of oil in the bore of a 3-in.70 G-9 gun decreases band wear.