The Nitro Express (NE) series of cartridges are used in large-bore hunting rifles, also known as elephant guns or express rifles, but later came to include smaller bore high velocity British cartridges.

An elephant gun is a large caliber gun, rifled or smoothbore, originally developed for use by big-game hunters for elephant and other large game. Elephant guns were black powder muzzle-loaders at first, then black powder express rifles, then later used smokeless powder cartridges.