Let's face it, duck hunting is not exactly the ideal place for a pretty shotgun.  With the constant water spray, raining, etc related to duck hunting coupled with the rough and tumble lifestlye that accompanies life in the duck blind, a shotgun is bound to suffer some rust problems from time to time.

The process is reasonably simple to do, but does require some attention to detail and a bit of patience.  I just had this exact problem and here is how I solved it.  At your local hardware / home store procure some #0000 (some refer to as four ought) steel wool.  Locate some penetrating oil (WD-40, Hoppes, or similar) and douse the rusted area(s) with the oil.  Allow to settle a minute or so.  With GENTLE pressure, use the steel wool to remove the rust.  I can't stress enough that it is better to have to do this many times than do it too hard and risk ruining the finish on your barrel.  Once you think you have done a good job, clean the entire outside of the barrel as you normally would and then check your work.  Odds are you missed a small portion of the rust.  If you look closely you will find it.  Rinse and repeat the process as described above as many times as it takes to remove the rust always making sure to rub gentle enough as to not ruin your barrel.  It may help to do this over the course of several days or weeks.  Once complete make sure to put a good rust inhibitor on the outside of the barrel to help keep the rust away.

What are your experiences with this or other method to remove rust from your shotgun?