I have a 1974 belgium browning 20 ga that is in immaculate shape, though it has been shot. I'm not sure how to grade, but it is easily a A-. How can i determine the value? I also have a 1960's or so sweet sixteen belgium with the round stock where you grip the gun. It is a B quality/condition gun. Would like to get appx values. Not interested in selling, just wondering value.