While you drive out a roll pin be careful to support the sight so you dont exert pressure on the screws holding the base. Regarding base screws, many times they have sealant in the threads. You can heat the screws by inverting the barrel, breaking the bond. As always, use a strong proper fitting screwdriver or driver bit. If you use a Weaver base---it is the 92a. And, keep the removed sights with a note as to their origin. rp