my girlfriends dad sold me a 22lr rifle that he believes is a research and development model of the mk 1. I have no idea what It is but it does have the savage info on it and it does have a weird marking on it where the barrel meets the receiver as well as a R D 91 stamped on the receiver. if you think you can help identify this as a real or fake savage gun please let me know I really want to know if it is a real research and development gun and if so how much is it potentially worth. thank you.