6mm Optimum

The 6mm AR (center) is near the "6mm Optimum".

The "6mm Optimum" is a concept popularized in 1999 by military writer Stanley C. Crist.

History

Crist argued for the adoption of a 6mm rifle chambering as a replacement for the venerable 5.56×45mm NATO and 7.62×51mm NATO, calculating that such a loading would be near the weight and minimal recoil of the lightweight 5.56 while nearer the terminal performance of the heavier 7.62, thereby permitting a single caliber to serve in general-purpose machine guns, sniper rifles, and infantry carbines.

Ballistics

Crist's specifications were that "6mm Optimum" ammunition achieve, with a 100 grain bullet:

  • velocity: 2,900fps (muzzle), 1149fps (1,200m)
  • energy: 1,867ft-lbs (muzzle), 293ft-lbs (1,200m)
  • flight-time to 1,200m: 2.21 seconds
  • deflection @ 1,200m in 10mph crosswind: 151 inches
  • maximum trajectory: 244 inches

...of which he noted, "...even with a conservative estimate for the muzzle velocity of the 6mm Optimum cartridge, computed data for 1200-meter velocity, flight-time, wind-deflection, and trajectory height are all greatly superior to both 5.56 and 7.62 NATO rounds."[1]

See also

References

  1. ↑ Crist, Stanley C. "Is 6mm The Optimum Caliber? A Common Cartridge for Rifle and Machinegun" (PDF). Infantry, Sept-Dec. 1999. 72 (3). Retrieved June 19, 2017.
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