I have a rifle that got wet in a flooded basement. It was sitting, butt down in water, for three days. The water was above the trigger guard. There is a stain that runs toward the butt from the rear action screw and from the rear sling swivel. The trigger guard is a cast allow and did not bleed onto the wood. The stock is an oil stock, no poly or plastic coatings.

Any suggestions on how to remove the stains?

Thanks in advance.

I've had pretty good results with wood bleach. It's oxalic acid dissolved in water. You should be able to find it at any good paint store in your area. It's used a lot for cleaning/removing stains on outdoor decking. I'd strip the stock down to bare wood first.