Further isolation and attenuation of shock can be achieved by the use of a special O-ring fitted to the grip screw. As the screw is tightened, the O-ring is forced downward and outward, imposing itself between the hexagonal flats of the bushing and the bore through the grip, providing additional cushioning between the grip and bushing.
With conventional bushings, there is insufficient space between the bushing and the bore to allow entry of a compressed O-ring, and the slot in the top of the bushing tends to quickly damage the O-ring.
Grip screws frequently loosen when shooting with G10 and other rigid and heavy grips. In these conditions, O-rings provide a high friction seat for the screw which minimizes loosening. The Challis Hex Drive Bushings are designed to enhance the performance of O-rings used for preventing screw extraction from discharge forces.
The grip screw O-rings supplied by Challis Grips are a special size manufactured specifically for use with grip screws. They will not prevent the grip screws from fully seating unlike the #60 O-rings commonly used in the past.