I bought an A5 at Cabelas that apparently was stored somewhere water rose to about half the butt stock. The gun was badly spotted with rust and apparently believed to be a salt gun because it was quite cheap. When I saw the round knob and the manufacturing date I knew it wasn't a salt gun and I believed the rust to be not of a serious nature. It has cleaned up beautifully to the nicest A5 I've ever owned as it was apparently used very little. However there is a water stain on the stock that will not sand out. I would like to take it back to it's original light chestnut color.

How do I handle the water stain with out going to a overall dark stain to cover it.