The safest way to do it is with a flat hand file at a 45 degree angle to the edge of the lug. to get the shape and then use various grades of sandpaper on a stick to get it smoothed out and then a polishing wheel - once you get a bit more brave you can try a grinding wheel on a dremell but one slip and its trouble lolI too would like to flatten and chamfer the case sides.
I'm not confident about grinding them flat.
Is there a good way to file them flat? (LOL.