I put three or four coats on my wife's A400 12g to protect the faux grain finish. The gun is about five years old. I used Pro Custom Oil which has Tung Oil. It is a wipe on finish. That was about three years ago. It worked well and looks good. It stood the test of time. No duck hunting though. It is used for sporting clays and has lots of use.

So many guns, so little time!