Someone correc me if Im wrong....even though you may not use or want the rear sight on your ML you must replace the screw (a new one) in place of the one you took out for the pourpose of barrel strength. Without the screw in place you cause it to be a weak spot in the barrel. I know this is true of Scope Screw Holes in the barrel so Im assuming it is the same for sight screw holes also....again I may be wrong.
(BP)