408 Cheytac Ammo For Sale

408 CheyTac Ammo (designated 408 Chey Tac (10.36×77mm) by the C.I.P. from 2013 to 2021) is a specialized rimless, bottlenecked, centerfire cartridge for military long-range sniper rifles that was developed by Dr. John D. Taylor and machinist William O. Wordman. The round was designed with a possible military need for a cartridge for anti-personnel, anti-sniper and anti-materiel roles with a (supersonic) precision range of 2,200 yards (2,000 m). It is offered as a competitor to the most common military NATO long-range service cartridges such as .338 Lapua Magnum and the .50 BMG.

.408 CheyTac Ammo is based on the .400 Taylor Magnum, which itself is based on a modified .505 Gibbs, necked down to 0.408 inches (10.36 mm). The .505 Gibbs is an old English big game cartridge that was designed to accommodate 39,160 psi (270 MPa) pressure. One of the disadvantages to these old cartridge cases intended for firing cordite charges instead of modern smokeless powder is the thickness of the sidewall just forward to the web. During ignition, the cartridge’s base, forward to the bolt face, is not supported. The case is driven back against the bolt face which results in the stretching of the case, particularly the sidewall immediately forward of the web. When the sidewall resists the outward expansion against the chamber, the pressure stretches the case thereby increasing its length resulting in the sidewall becoming thinner at that stretch point.