A friend gave me a rifle to check out. He inherited it, along with some others that we are going through one at a time. This one is a Winchester Model 90. I started researching about it and found that some of them can be worth some money. I am aware that if you clean/refurbish/alter a valuable vintage gun, it can devalue it substantially. How can I ascertain if his particular rifle is valuable? I did a quick search and this model 90 was manufactured in 1915. Has the take-down screw and is chambered in 22 WRF. What else do I need to check? Thanks for any help.
