The 408 Cheyenne tactical metric designation is a CheyTac 10.36 × 77mm. Also, it is a specialized rimless bottlenecked centerfire cartridge. Dr. John D. Taylor and Willam O. Wordman developed it. It has its place of origin in the United States and was designed in 2001. CheyTac USA LLC manufactures it. It has remained in production from the design year 2001, up till present day.
It is ammo for the military long-range sniper rifle and has a bullet diameter of 10.36mm. It possesses a neck of 11.12mm and has a shoulder of 15.24mm. It also has its rim diameter at 16.25mm, and with a rim thickness of 1.60mm, it boasts an overall length of 115.50mm with a rifling twist of 330.2mm. The .408 CheyTac Ammo has a maximum pressure of 440.00MPa.
With a bullet mass of 305gr, the .408 CheyTac Ammo travels at a velocity of 3,590 ft/s and delivers up to 11,247 joules of energy. A bullet mass of 419gr travels at 3,000 ft/s, and the energy delivered is 11,352 joules.
The .408 CheyTac Ammo delivers very accurate performance from a sniper rifle. It also has solid copper bullets. It has the least bullet drop amongst a family of sniper rifles. This is due to its superior aerodynamics. The .408 CheyTac Ammo's low drop makes it ideal for dispatching targets at very long ranges. In addition, it provides downrange performance, which is made possible by using a premium high BC projectile.