I have what I think is a 2nd generation Colt 1851 revolver. C1121 series, serial # 9xxx. What I need to know is what is it worth, it appears to be unfired, but I think the front sight has been replaced. Comes in the box with all the company paper work. Whats really throwing me is it has a steel squared back strap, all my books say it should be silver or brass.