.408 Cheyenne Tactical
| .408 Cheyenne Tactical | ||||||||||||
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.408 Cheyenne Tactical cartridge | ||||||||||||
| Type | Rifle | |||||||||||
| Place of origin | United States | |||||||||||
| Production history | ||||||||||||
| Designer | John Taylor and William O. Wordman | |||||||||||
| Designed | 2001 | |||||||||||
| Manufacturer | CheyTac USA LLC | |||||||||||
| Produced | 2001–present | |||||||||||
| Variants | .375 CheyTac | |||||||||||
| Specifications | ||||||||||||
| Parent case | .505 Gibbs/.400 Taylor Magnum | |||||||||||
| Case type | Rimless, bottleneck | |||||||||||
| Bullet diameter | 10.36 mm (0.408 in) | |||||||||||
| Land diameter | 10.16 mm (0.400 in) | |||||||||||
| Neck diameter | 11.12 mm (0.438 in) | |||||||||||
| Shoulder diameter | 15.24 mm (0.600 in) | |||||||||||
| Base diameter | 16.18 mm (0.637 in) | |||||||||||
| Rim diameter | 16.25 mm (0.640 in) | |||||||||||
| Rim thickness | 1.60 mm (0.063 in) | |||||||||||
| Case length | 77.21 mm (3.040 in) | |||||||||||
| Overall length | 115.50 mm (4.547 in) | |||||||||||
| Case capacity | 10.32 cm3 (159.3 gr H2O) | |||||||||||
| Rifling twist | 330.2 mm (1 in 13 in) | |||||||||||
| Primer type | Large rifle | |||||||||||
| Maximum pressure (C.I.P. (2013–2021)) | 440.00 MPa (63,817 psi) | |||||||||||
| Ballistic performance | ||||||||||||
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| Source(s): Cartridges of the World | ||||||||||||
The .408 Cheyenne Tactical (designated 408 Chey Tac (10.36×77mm) by the C.I.P.) 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.