I've always wondered about converting a fixed sight Smith to adjustable. I've always thought you would have to mill the trough out then cut a dovetail then find a taller than normal rear. upon further thought I guess you could just cut a dovetail through the trough. It would leave a gap under the new rear sight but shouldn't really matter? specifically thinking about a M65. The trough is fine for combat but I don't like the sight picture for more precise shooting.