Congratulations, you did well with picking up this 19-3 for a fair price. From your pictures, I don't see any mild corrosion unless it's in the cylinder holes or under the wooden stocks. Remove the stocks, and clean your revolver with Hoppe's No. 9 or other suitable Clean-Lube-Preserve product (Ballistol, TetraGun, Breakthrough, etc.). Bronze brush for the cylinder and barrel bore, and bronze wool (in a pinch you can use 0000 steel wool) with very light pressure for any surface rust/corrosion. Those CLP cleaners work well on cleaning the internal parts, too. A good waxing with Renaissance Wax (or Johnson's Paste Wax) after cleaning will make that baby shine! Enjoy!