Rumbul Magnesium Bullets are moulded metal cylinders of a magnesium/aluminium/copper alloy (86, 12 and 2% respectively) weighted with iron shot. Bullets intended for adult cattle (2.5 cms dia. x 7.6 cms length) each contain 40 g magnesium. Smaller bullets (1.9 cms dia. x 4.6 cms length) each contain 15 g magnesium and are intended for adult sheep or calves. After swallowing they lie in the reticulum or at the base of the rumen and break down, releasing magnesium continuously by electrolytic action (which prevents the formation of insoluble deposits), throughout their active life. The iron shot is eliminated in the faeces of the animal as small discrete particles.