4X Medium-Duty Offest Handle .401 Shank Riveting Hammer. These rivet hammers are among the most popular for aircraft riveting. Easily controlled, slow, heavy blows deliver just the right impact to form the rivet head without excessive work hardening of the rivet or stretching the surrounding metal. Also handy for light chipping, scraping, metal cutting, peening and other hammering applications. All riveters are equipped with quick change and beehive retainer springs and feature removable front bushings. by installing HG-50215.401 special bushing.