The .577 Nitro Express was descended from the .577 Black Powder Express, a cartridge invented by the late Samuel Baker who had Holland Holland build him an express rifle in this caliber.This caliber is generally used for thick-skinned dangerous game such as elephant, rhino, Cape buffalo. Even among professional ivory hunters of old it is typically treated as an emergency weapon carried by the hunters gun bearer, reserved for stopping the charge of an enraged, wounded elephant in thick bush.
The HK 4.6×30mm cartridge is a type of ammunition used in the Heckler & Koch MP7 Personal Defense Weapon (PDW) and by the canceled HK UCP pistol. It is designed to minimize weight and recoil while increasing penetration of body armor. It features a bottlenecked case and a pointed, steel-core, brass-jacketed bullet.