[citation needed] The 6mm AR takes advantage of the wide variety of 6.2 mm (.243 in) caliber bullets.

[citation needed] 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 6.5 g (100 gr) or heavier grain projectile at 880 m/s (2,900 ft/s) (satisfying the "6mm Optimum").

[citation needed] These wildcats also push forward the shoulder of the same necked Grendel case similar to the Turbo 40, yielding more powder capacity.

[citation needed] Similar to the 6mm Turbo 40 and 6mm FatRat, the 6mm Grinch has a blown-forward shoulder on par with the 6mm Dasher to eke maximum powder capacity from the necked Grendel case.