Thread: New 6mm ARC from Hornady

I stand corrected..
In true Hornady fashion they have not just necked down a grendel case.
To maximize on factory ammo, dies and brass sales they have made the base to shoulder dimension shorter than the grendel case but longer than the 6ppc case.

The 6mm ARC is judging by the SAAME listed case head dimensions and the Maximum Average Pressure (MAP) of 52,000 psi, it is based on the .220 Russian case (like the 6.5 Grendel or 6mm PPC). At first glance, the 30-degree shoulder angle and the shoulder diameter of .4301″made me think that 6mm ARC is a necked down 6.5 Grendel, however, the length to shoulder is 1.1207″ which is shorter than 6.5 Grendel’s 1.1507″ (and longer than 6mm PPC’s 1.075″).
The maximum cartridge overall length of 2.26″ (57.4mm) is identical to the max COAL of .223 Remington which means 6mm ARC is designed to be an AR cartridge. The case length of 1.49″ results in a lot of bullet space (.77″ or 3.16 calibers) which will allow loading projectiles with very long ogives and great external ballistic performance. The SAAMI drawing states a muzzle velocity of 2,700 fps for 108-grain bullets.

243 caliber cartridges based on the .220 Russian case have been successfully used by competition shooters with the most popular of them probably being the 6mm PPC. There are several variations of 6mm PPC in the CIP standards, however, oddly enough, neither 6mm PPC nor any of its siblings are standardized by SAAMI. That being said, the 6mm ARC looks like an attempt to have a SAAMI standard cartridge of this very successful case and caliber combination.