The .458 Winchester Magnum is a belted, straight-taper cased, big five game rifle cartridge. It was introduced commercially in 1956 by Winchester and first chambered in the Winchester Model 70 African rifle. It was designed to compete against the .450 Nitro Express and the .470 Nitro Express cartridges used in big bore British double rifles. The .458 Winchester Magnum remains one of the most popular large game cartridges, and most major ammunition manufacturers offer a selection of .458 ammunition. History The .458 Winchester Magnum was designed for hunting dangerous game animals by emulating the performance of powerful English double rifle cartridges in a bolt-action rifle. The use of a bolt-action rifle offered hunters a cheaper alternative to the big-bore double rifle, and ammunition could be manufactured using available tooling. The .458 Winchester Magnum soon became a success as dangerous game hunters adopted the cartridge. Soon game wardens, wildlife managers, and professional hunters switched to the .458 Winchester Magnum as their duty rifle. The cartridge would become the standard African dangerous game cartridge in short order. By 1970 issues with the cartridge began to surface. Winchester had been using compressed loads of ball powder as a propellant for .458 Winchester Magnum. Due to clumping of the powder charge and the erratic burn characteristics associated with such loads, performance of the cartridge came into question. While Winchester addressed this issue, the stigma remained, and the cartridge's performance on dangerous game was suspect. However, the .458 Winchester Magnum remained the standard of measure for dangerous game cartridges. Recently, other .458 cartridges and various .416 cartridges have gained wider acceptance, but the 458 Win Mag remains one of the popular choices. Specifications The .458 Winchester Magnum was designed from the outset to duplicate the performance level of the .450 Nitro Express and the .470 Nitro Express, which had become the mainstay of African dangerous game hunters. The .450 Nitro Express had been rated to launch a bullet at out of a barrel while the .470 Nitro Express would launch a bullet at out of a barrel. The design criteria for the .458 Winchester Magnum called for it to launch a bullet at out of a barrel. SAAMI compliant .458 Winchester Magnum cartridge schematic: All dimensions in inches [millimeters]. The .458 Winchester Magnum's case was based on a .375 H&H case shortened to and renecked (to reduce taper) to accept a bullet. The cartridge remains