M200 CHEYTAC INTERVENTION

Type	Sniper rifle
Place of origin	United States

Used by See Users

Manufacturer	CheyTac LLC
Produced	2001—present
Variants	M-200 M-200 Carbine M-200 CIV (Civilian) M-200 RK M-310 SS (Single Shot) M-310 R (Repeater)

Weight	31 lb (14 kg) without scope (M-200)
Length	53 in (1.34 meters) (stock extended), 46¾ in (1.18 m) (stock collapsed) (M-200)
Barrel length	29 (73.7 cm) in standard w/ 1:13 twist (M-200), 26 in (66 cm) optional.

Cartridge	.408 Chey Tac or .375 Chey Tac
Action	turn-bolt
Effective range	2000+ m - M-200 2000+ m - M-200 Carbine 1500+ m - M-200 CIV (Civilian) 1800+ m - M-310 SS (Single Shot) ) 1800+ m - M-310 R (Repeater)
Feed system	7-round detachable box magazine
Sights	day or night optics

CheyTac L.L.C researched the optimum cartridge case, bullet and barrel configuration for very long range use. For this the .408 Chey Tac cartridge was developed that fires very-low-drag mono metal bullets that were specially designed for the Long Range Rifle System by the now (2010) defunct company, Lost River Ballistic Technologies.
Lost River Ballistic Technologies inventor, Mr. Warren Jensen, stated that "the .408 Chey Tac was the first bullet/rifle system that utilizes a balanced flight projectile. To achieve balanced flight the linear drag has to be balanced with the rotational drag to keep the very fine nose (meplat) of the bullet pointed directly into the oncoming air. It should result in very little precession and yaw at extreme range and allows accurate flight back through the transonic region. This is hard to achieve for small arms projectiles. Mathematically you are at a great disadvantage trying to achieve balanced flight with a lead core non mono metal bullet. The rotational mass/surface area ratio is too high."
The balanced flight projectile patent can be found at the US Patent Office, Controlled spin projectile, US PAT No. 6,629,669. According to the patent, a projectile engraved and launched according to the specifications of the patented invention should decelerate from supersonic flight through transonic to subsonic in a stable and predictable manner effective to a range beyond 3,000 yards (2,743 m). It implies that, amongst several other preconditions, the rifle barrel has to have specific rifling dimensions to achieve a desired amount of axial air drag on the bullet's surface, which reduces the bullet's spinrate to achieve balanced flight.
To achieve balanced flight the rifling twist rate for the .408 CheyTac chambering was chosen at 330.2 mm (1 in 13 in), with eight 0.4080 in diameter grooves, 0.4010 in diameter bore and a 0.050" land width, square cut, with no taper. The later .375 CheyTac round, developed from the .408 CheyTac, uses a 292 mm (1:11.5 in) rifling twist rate.