)[3] 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.

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.

The .408 Cheyenne Tactical became officially registered by the Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P.)

(Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings the .408 Cheyenne Tactical can handle up to 440.00 MPa (63,817 psi) Pmax piezo pressure.

Practically there can be some muzzle velocity gained by this method, but the measured results between parent cartridges and their "improved" wildcat offspring is often marginal.

[6] The wildcat status of the .375 CheyTac ended on 17 May 2017 when it got Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P.)

[8] She was assisted by Shane Bryan, who acted as a spotter, giving targeting-correction advice, based on his observation of bullet impact.

The oldest factory .408 CheyTac ammunition uses bullets designed by Warren S. Jensen and originally produced by Lost River Ballistic Technologies.

Currently (2009) these projectiles are produced by Jamison International, where they are turned on Swiss-type CNC lathes from solid bars of proprietary copper nickel alloy.

One noted downside to the use of solid mono metal projectiles is that they tend to increase the fouling left in the rifle barrel after they are fired.

This inevitably reduces the seal of the bullet in the barrel, allowing hot gunpowder gases to reach the sides of the projectile, vaporizing some of the material and depositing it in the bore.

In 2007 Dr. John D. Taylor designed a new class of armor-piercing projectiles known as the .408 CheyCorey and in this configuration, it outperforms the .50 AP (both black and silver tips) cartridge against armor steel and titanium.

Some more explanation about the transient nature of a projectile's G1 BC (it rises above or gets under a stated average value for a certain speed-range regime) during flight can be found at the external ballistics article.

Lost River Ballistic Technologies (statement of Mr. Warren Jensen) stated that "the .408 CheyTac is the first bullet/rifle system that utilizes what they call a balanced flight projectile.

In other words, any bullet with appropriate drag behaviour around Mach 1 and mass (distribution) will do exactly what the balanced flight projectile patent states.

[13] For a typical .408 CheyTac chambered gun, shooting 27.15 gram (419 gr) Lost River Ballistic Technologies bullets (claimed G1 BC = 0.940) at 884 m/s (2900 ft/s) muzzle velocity, the supersonic range would be 1,930 m (2,110 yd) under International Standard Atmosphere sea level conditions (air density ρ = 1.225 kg/m3).

For a typical .375 CheyTac chambered gun, shooting 24.30 gram (375 gr) Lost River Ballistic Technologies bullets (claimed G1 BC = 1.02) at 930 m/s (3050 ft/s) muzzle velocity, the supersonic range would be 2,230 m (2,440 yd) under International Standard Atmosphere sea level conditions (air density ρ = 1.225 kg/m3).

[17] In theory, Mr. Möller calculated that a typical .375 CheyTac chambered gun, shooting his now defunct 26.44 gram (408 gr) .375 Viking bullets (claimed G1 BC = 1.537) at 870 m/s (2854 ft/s) muzzle velocity, would have a supersonic range of 3,090 m (3,380 yd) under International Standard Atmosphere sea level conditions (air density ρ = 1.225 kg/m3).

[citation needed] It would appear that Mr. Möller did not test this projectile prior to public release whereby the dynamic instability would have been discovered.

Such rifles are ordered by long-range accuracy oriented shooters and built by specialized, highly skilled gunsmiths and can cost thousands of dollars.