Shooting skeet today with my recently acquired 12 gauge Beretta SO-3 O/U, I suddenly discovered that the right lock had failed to cock and continued to do so, despite all my efforts to persuade it to relent. When I got the gun home, I discovered that none of my motley selection of screwdrivers fit the extremely thin slotted screws on the right sidelock. I ground one down to make a passable fit and was able to remove the rear screw, but the front screw stubbornly resisted my efforts to budge it, and rather than risk damaging or defacing it, I ceased my efforts, pending acquisition of the proper tool.

Can anyone suggest a source for a set of screwdrivers with wide enogh and thin enough blades to use on such a finely made piece of machinery?