I used some Dura coat on a scope once . I used coyote tan on it it was an expensive scope a guy said he wanted to buy it but didn't like the paint job . I took the lens caps off and applied some Critry clean to them . they cleaned right up leaving them nice and finished as they had been when new . So I did the rest of the scope with it and it cleaned up well didn't affect the o-rings either I was very careful around the lens though . When I have used camo tape and had the need to clean the glue residue off , I have found that a small amount of charcoal lighter fluid on a paper towel did it well and didn't harm the finish on my stock . But I didn't leave it setting on the stock for an extended amount of time either , rubbing the glue with the towel then moving to another area and cleaning it . wiping the areas with a clean towel after the glue was removed .