I need some advice on fitting a new front sight to my Merkel double rifle. These fit in a longitudinal slot and are inserted from front and tapped in towards the rear. The replacement is larger, and will not fit the dovetail slot without reducing the width at the base of the blade. What method do experienced members here use to file the sight to fit the slot in the ramp on the barrel? I read somewhere that the base of the sight blade can be rubbed on a piece sandpaper to reduce height and therefore also reduce width as the bottom (widest) part is slowly removed. It does seem simpler than trying to file the sides while matching the angles. Your suggestions?