The Ruger system for holding the sight in the dovetail consists of a screw thru a circular bushing with a bevel on the side that faces the sight's dovetail in the rib.
Some of the ones I removed; moved with a finger, others were still tight because the little bushing was pretty much swaged down into its cavity. The bushing is fairly dainty, and probably could be expanded fairly easily to a tightness in the rib cavity. On the ones that were tight, a good rap with a non marring punch/hammer did the trick for my attempts. However, some care in the rapping is prudent. I have seen some that the screw stripped out, others with the bushing swaged in.
The fitment of the bushing to the dovetail and its cavity is fairly tight to begin with, then pressure with the screw is applied, and it gets tighter. Sometimes there is some corroision on the two surfaces, that makes the sight hard to drift with the screw out etc.
One might try a little Kroil on the circular insert bushing to see if that would get under the tight fitments, then give some judicious raps. Sometimes shock will do the trick, but perhaps a little patience will show fruit.
I wish you good luck with it.
Roof
