A friend brouhgt me a shotgun to look at and see if it's wroking correctly. it's a Stevens Savage .410 3" single shot. The gun is working correctly I dry fired it with a spent shell. No rust an what appers to be a heat blued receiver. He is wondering what it's worth? I have one of my own but not as nice and thought I'd ask for some help with value and how to find the age of the gun?