martyrd: I don't think there is enough metal on either the slide or barrel of those little pocket rockets to add a pair of adjustable sights. As for some sort of a scope - it would be bigger than the whole gun and I think you would have to use a pistol grip type mount that you find on occassion for the 45 autos, but sufficiently downsized to fit the Model 21. Also, although I love those little pistols I don't think there is enough inherent accuracy in those small frame guns to merit scoping one. I think your project would be very expensive, possibly deleterious to the pistol and not very satisfying in the accuracy department. Sorry, but I HTH. Mikey.