The 6mm Advanced Rifle Cartridge (6×38mm), or 6mm ARC for short, is a
6 mm (.243) caliber intermediate rifle cartridge
A rifle cartridge is a firearm cartridge primarily designed and intended for use in a rifle/carbine, or machine gun.
Types Full-powered
A full-powered cartridge is a rifle cartridge used interchangeably between service rifles, sniper rifles ...
introduced by
Hornady
Hornady Manufacturing Company is an American manufacturer of ammunition cartridges, components and handloading equipments, based in Grand Island, Nebraska.
History
The company is currently run by Joyce Hornady's son, Steve Hornady, who took over ...
in 2020, as a low-
recoil
Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force requ ...
, high-
accuracy
Accuracy and precision are two measures of ''observational error''.
''Accuracy'' is how close a given set of measurements (observations or readings) are to their ''true value'', while ''precision'' is how close the measurements are to each other ...
long-range cartridge
Cartridge may refer to:
Objects
* Cartridge (firearms), a type of modern ammunition
* ROM cartridge, a removable component in an electronic device
* Cartridge (respirator), a type of filter used in respirators
Other uses
* Cartridge (surname), a ...
, designed for use in the
AR-15
An AR-15-style rifle is any lightweight semi-automatic rifle based on the Colt AR-15 design. The original ArmaLite AR-15 is a scaled-down derivative of Eugene Stoner's ArmaLite AR-10 design. The then Fairchild Engine and Airplane Corporation d ...
platform at request of a specialized group within the U.S. DoD for its multipurpose combat rifle program.
Performance
The cartridge makes use of 6 mm (.243 in)
bullet
A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...
s, which are known for their high
ballistic coefficient
In ballistics, the ballistic coefficient (BC, ''C'') of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the d ...
s due to the high
sectional density
Sectional density (often abbreviated SD) is the ratio of an object's mass to its cross sectional area with respect to a given axis. It conveys how well an object's mass is distributed (by its shape) to overcome resistance along that axis.
Sectio ...
with less
drag and better
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
retention at extended ranges. With the release in 2020, Hornady also launched three factory loads with bullet weights and advertised G1 ballistic coefficients of .512, .530 and .536 respectively.
The 6mm ARC is a medium-power cartridge comparable to the
6.5mm Grendel
The 6.5mm Grendel is an intermediate cartridge jointly designed by British-American armorer Bill Alexander, competitive shooter Arne Brennan (of Houston, Texas) and Lapua ballistician Janne Pohjoispää, as a low-recoil, high-precision rifle cart ...
, but with better ballistics thanks to the greater muzzle velocity achieved by using lighter 6 mm bullets and enough power to make use of the heavy 6 mm bullets. Some have stated that it offers comparable ballistics to larger 6 mm cartridges like the 6mm Creedmoor and
.243 Winchester, but out of a smaller cartridge, however this simply is not true when comparing muzzle velocities between them. What the 6mm ARC does offer though is almost comparable velocities and ballistic performance, but out of a compact cartridge that has lessened perceived recoil and fits into the standard
AR-15
An AR-15-style rifle is any lightweight semi-automatic rifle based on the Colt AR-15 design. The original ArmaLite AR-15 is a scaled-down derivative of Eugene Stoner's ArmaLite AR-10 design. The then Fairchild Engine and Airplane Corporation d ...
length actions.
In addition to the above comments there is some confusion regarding the 6 mm ARC's performance. This is because loading data given in some manuals such as the ''11th Edition Hornady Reloading Manual'' ,for example, has two sets of data. The first set of data is loaded to the SAAMI maximum average pressure (MAP) of 52,000 psi, which is stated to be suitable for gas-operated firearms such as the AR-15 platform and its derivatives. The second set of data is loaded to a MAP of 62,000 psi, which is stated to be for use with bolt action guns such as the
CZ 527
The CZ 527 is a bolt-action smallbore rifle designed by Česká zbrojovka Uherský Brod. CZ discontinued production in 2021. There are numerous different designs and stylings. The available calibers (though not every rifle is designed for each o ...
. The Hornady manual states that this second set of data should not be used in gas-guns. Due to the lower MAP, the performance of 6mm ARC ammunition loaded to gas-gun pressures will, on average, be less than firearms loaded to bolt action pressures when using the same barrel length. When using shorter barrels, which are common on gas-guns, the difference will be even more pronounced.
For example, the data in the Hornady 11th Edition Manual for an 18 in (457 mm)-barrelled AR-15 platform firearm was on average 200-300 ft/s (60-90 m/s) less than the data for the 24 in (610 mm)-barrelled CZ 527 bolt action rifle.
SAAMI spec
Compatibility with the AR-15
For an ordinary AR-15 rifle chambered for the
.223 Rem
The .223 Remington (designated as the 223 Remington by the SAAMI and 223 Rem by the CIP) is a rimless, bottlenecked rifle cartridge. It was developed in 1957 by Remington Arms and Fairchild Industries for the U.S. Continental Army Command ...
/
5.56mm NATO, a new
barrel
A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
,
magazine
A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
and
bolt are required to convert to the 6mm ARC. The 6mm ARC utilizes the same bolt head size as the
6.5mm Grendel
The 6.5mm Grendel is an intermediate cartridge jointly designed by British-American armorer Bill Alexander, competitive shooter Arne Brennan (of Houston, Texas) and Lapua ballistician Janne Pohjoispää, as a low-recoil, high-precision rifle cart ...
, and 6.5mm Grendel-compatible
AR-pattern box magazine
A magazine is an ammunition storage and feeding device for a repeating firearm, either integral within the gun (internal/fixed magazine) or externally attached (detachable magazine). The magazine functions by holding several cartridges withi ...
s have also been used successfully with the 6mm ARC.
gununiversity.com , 6mm ARC Released / Hands-On Testing and Comparisons, by Ryan Cleckner 3 June 2020
/ref> The 6mm ARC therefore can also be a suitable chambering for shorter "micro-action" bolt-action rifle
Bolt-action is a type of manual firearm action that is operated by ''directly'' manipulating the bolt (firearms), bolt via a cocking handle, bolt handle, which is most commonly placed on the right-hand side of the weapon (as most users are r ...
s.
See also
* .223 Remington
The .223 Remington (designated as the 223 Remington by the SAAMI and 223 Rem by the CIP) is a rimless, bottlenecked rifle cartridge. It was developed in 1957 by Remington Arms and Fairchild Industries for the U.S. Continental Army Command ...
* 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 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 service rifle chambering as a replacement for the venerable 5.56×45mm NATO and 7.62×51mm NATO, calculati ...
", a concept of a 6 mm cartridge bridging the gap between the 5.56×45mm NATO and 7.62×51mm NATO cartridges
* 6 PPC
References
{{7.62×39derivatives
Pistol and rifle cartridges