Locktite is basically a lacquer, if I recall correctly. For some sights, particularly those that are attached with a set screw, heat is the thing. A soldering iron applied to the set screw does the trick.
I don't recall how the sights on P7s are attached. Is it in a dovetail slot? Also, are the slots tapered (some sights only go in one way and out the other, so you have to know what direction to pound)?
