|Place of origin||United States|
|Parent case||6.5 Grendel|
|Case type||Rimless, bottleneck|
|Bullet diameter||.243 in (6.2 mm)|
|Neck diameter||.271 in (6.9 mm)|
|Shoulder diameter||.4323 in (10.98 mm)|
|Base diameter||.4433 in (11.26 mm)|
|Rim diameter||.4449 in (11.30 mm)|
|Rim thickness||.0591 in (1.50 mm)|
|Case length||1.525 in (38.7 mm)|
|Overall length||2.260 in (57.4 mm)|
|Case capacity||36 gr H2O (2.3 cm3)|
|Primer type||Small rifle|
The 6mm AR takes advantage of the wide variety of .243 in. caliber bullets. Slim, long bullets with high ballistic coefficient are ideal for energy retention at long ranges.
It is similar to the 6PDK which also uses a 6mm bullet and a similar muzzle energy and case capacity to the 6mm AR and 6.5 Grendel, in a casing somewhat popular for the AR-15, a necked-down 6.8mm Remington SPC casing.
6mm AR Turbo 40 Improved
This variant uses an Ackley Improved fire formed case with less tapering and a 40-degree higher shoulder permitting a larger powder capacity. It is claimed by its maker to be capable of driving a 100+ grain projectile at 2900ftp (satisfying the "6mm Optimum").
6mm Rat and FatRat
These wildcats also push forward the shoulder of the same necked Grendel case similar to the Turbo 40, yielding more powder capacity. 100+ grain VLD boat-tail bullets have to be seated deeply within the case neck, however, rendering some of these volume gains illusory.
Similar to the Turbo 40 and FatRat, this has a blown-forward shoulder on par with the 6mm Dasher to eek maximum powder capacity from the necked Grendel case. In 2016, Greg King won a National Bench Rest Shooters Association event with a "Grinch" wildcat, besting a field of mainly 6mm PPC competitors.
- ammoseek rankings: 
- http://www.6mmar.com/6mmAR_Turbo_40_Improved.php Shooting the 6mmAR Turbo 40° Improved
- http://forum.accurateshooter.com/threads/6mm-grinch-defeats-entire-field-of-6ppcs.3912901/ 6MM GRINCH Defeats entire Field of 6PPCs
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