i drilled and used the mounting screws to tap the holes for my saito 120,i drilled the holes two sizes under the screw size.once i tightened the screws and let me say a few of them i had to put in by hand wore my wrist out.they have been in now for two years and i checked them every time i went to the field for looseness for about a month,now i will check one screw every now and then.in fact i dread if i ever have to take them back out.lock nuts for peace of mind wouldn't hurt but IMO they aren't needed.