Here are three photos of a 1/2-13 "home-made bolt"
that has had intentional damage to it's seating surface.

The second photo shows the damage to the flat washer when the Schirr-Lock Quick Locking Fastener was torqued to 175 Lb-ft.(recommended torque is
54 Lb-ft to achieve 5853 Lbs clamp.)

The third photo shows the Schirr-Lock nut seated
solidly and safely to full torque standards