The .408 Chey Tac as it is commonly known or its full name .408 Cheyenne Tactical is a counter sniper rifle cartridge, developed by Dr. John D. Taylor and machinist William O. Wordman. This cartridge was designed specifically for market to the military in hopes it would be both a cost effective and ballistically superior round to the existing military long-range cartridges; the .338 Lapua Magnum and .50 BMG.