High Quality Content by WIKIPEDIA articles! The 9.3x64mm Brenneke (also unofficially known as the 9.3 x 64) is a rimless bottlenecked centerfire cartridge developed for big game hunting. The 9.3 denotes the 9.3 mm bullet diameter and the 64 denotes the 64 mm case length. Using the bullet diameter is unusual in German cartridge designations. Normally the approximate land diameter of the barrel is used for such designations.