The "6mm Optimum" is a concept popularized in 1999 by military writer
Stanley C. Crist.
History
Crist argued for the adoption of a
6mm
This is a list of firearm cartridges which have bullets of a caliber between and .
*''Length'' refers to the cartridge case length
*''OAL'' refers to the overall length of the cartridge
Measurements are in millimeters then inches, i.e. ''mm (in ...
service rifle
A service rifle (or standard-issue rifle) is a rifle a military issues to regular infantry. In modern militaries, this is typically a versatile and rugged battle rifle, assault rifle, or carbine suitable for use in nearly all environments. Most ...
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 (.223 caliber) while nearer the terminal performance of the heavier 7.62, thereby permitting a single cartridge to serve in
general-purpose machine gun
A general-purpose machine gun (GPMG) is an air-cooled, usually belt-fed machine gun that can be adapted flexibly to various tactical roles for light and medium machine guns. A GPMG typically features a quick-change barrel design calibered for v ...
s,
sniper rifle
A sniper rifle is a high-precision, long-range rifle. Requirements include accuracy, reliability, mobility, concealment and optics for anti-personnel, anti-materiel and surveillance uses of the military sniper. The modern sniper rifle is a por ...
s, and infantry
carbine
A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges.
The smaller size and lighter ...
s.
Ballistics
Crist's specifications were that "6mm Optimum" ammunition achieve, with a bullet:
*Muzzle velocity:
*Velocity at 1200 m: (slightly over the
speed of sound
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as w ...
)
*Muzzle energy:
*Energy at 1200 m:
*Flight-time to 1200 m: 2.21 seconds
*Deflection at 1200 m: in
wind speed
In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer.
Wind speed ...
*Maximum trajectory height:
...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."''
See also
*
Ballistic table
A ballistic table or ballistic chart is a tool which predicts the trajectory of a projectile, and is used to compensate for physical effects in order to increase the probability of the projectile reaching the intended target. Ballistic tables are ...
*
5.8×21mm (6mm bullet diameter)
*
5.8×42mm (6mm bullet diameter)
*
6mm PPC
The 6mm PPC (Palmisano & Pindel Cartridge), or 6 PPC as it is more often called, is a centerfire rifle cartridge used almost exclusively for benchrest shooting. It is one of the most accurate cartridges available at distances of up to 300 met ...
*
6mm AR
The 6mm AR is a centerfire wildcat cartridge initially designed by Robert Whitley for long-range performance in an AR-15 rifle.
Description
The cartridge uses a 6.5 Grendel case that has been necked-down to accept a 6.2 mm (.243 in) bullet ...
*
6mm ARC
The 6mm Advanced Rifle Cartridge (6×38mm), or 6mm ARC for short, is a 6 mm (.243) caliber intermediate rifle cartridge introduced by Hornady in 2020, as a low-recoil, high-accuracy long-range cartridge, designed for use in the AR-15 platform a ...
*
.243 Winchester Super Short Magnum
The 243 Winchester Super Short Magnum or 243 WSSM is a rifle cartridge introduced in 2003. It uses a .300 WSM (Winchester Short Magnum) case shortened and necked down to accept a .243in/6mm diameter bullet, and is a high velocity round based ...
*
6 mm XC
*
6×45mm SAW
The 6×45mm SAW describes an experimental series of rimless bottlenecked intermediate cartridges developed in the 1970s for the U.S. Army. The cartridges were produced in a variety of sizes and from a variety of materials. The intent was to dev ...
*
6-6.5x47 Lapua
*
6mm Lee Navy
The 6mm Lee Navy (6×60mmSR), also known as the 6mm U.S.N.Hanson, Jim, ''The 6mm U.S.N. - Ahead Of Its Time'', ''Rifle Magazine'', Vol. 9, No. 1 (January–February 1977), pp. 38-41 or .236 Navy, is an obsolete American rifle cartridge. It was ...
*
6 mm caliber
This is a list of firearm cartridges which have bullets of a caliber between and .
*''Length'' refers to the cartridge case length
*''OAL'' refers to the overall length of the cartridge
Measurements are in millimeters then inches, i.e. ''mm (in ...
*
List of rifle cartridges
List of rifle cartridges, by primer type, calibre and name.
File:Cartridge Sample 2.jpg, 350px, From left to right: 1 .17 HM2,2 .17 HMR, 2.5 .17 wsm, 3 .22LR, 4 .22 WMR, 5 .17/23 SMc, 6 5mm/35 SMc, 7 .22 Hornet, 8 .223 Remington, 9 .223 WSSM ...
*
Table of handgun and rifle cartridges
This is a table of selected pistol/submachine gun and rifle/machine gun cartridges by common name. Data values are the highest found for the cartridge, and might not occur in the same load (e.g. the highest muzzle energy might not be in the same ...
References
{{reflist
Pistol and rifle cartridges