T 7561 (OTTO) Tungsten slug, 3.175mm (0.125in) dia x 3.175mm (0.125in) length, 99.97% Cas 7440-33-7 - used in kinetic energy penetrators as an alternative to depleted uranium, in applications where uranium's radioactivity is problematic even in depleted form, or where uranium's additional pyrophoric properties are not required (for example, in ordinary small arms bullets designed to penetrate body armor).