6MM ARC

After using a 6.5 Grendel to cull a goodly number of Texas feral hogs, I’ve developed a great deal of respect for the cartridge. This has mostly involved nighttime forays shooting with thermal imaging optics. The 2.26-inch confines inherent to AR-15 magazines, and the Grendel’s limited case capacity, make 123- to 130-grain bullets the practical upper limit for such activities. These projectiles chug along at around 2,350/2,450 feet per second (fps), but deliver well out of proportion to its diminutive size.

- PATRICK MEITIN

Now, take the 6.5 Grendel case, neck it to 6mm, give firearms fast rifling to handle long-for-caliber bullets weighing from 103 to 115 grains, including ballistic coefficients (BC) equaling those 6.5 projectiles, and you have Hornady’s spanking-new 6mm Advanced Rifle Cartridge, or ARC.

As the story goes, Hornady developed the 6mm ARC under direction from the U.S. Department of Defense, optimizing the Grendel case to meet prescribed goals. The case head remains .441 inch and the rim is .059-inch thick. The neck was set back, allowing more room for long-for-caliber 6mm projectiles in standard AR magazines. The shoulder angle was set at 30 degrees. The cartridge was quickly accepted as a Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) standard, an excellent start to such a new cartridge. It could easily be argued the ARC is yet another version of the 6mm PPC (which was never SAMMI standardized) – actually a pretty fair assessment, though the fast rifling twist changes everything.

Hornady launched the 6mm ARC with three factory loads: a 103-grain ELD-X Precision Hunter at an advertised 2,800 fps, 105-grain BTHP Hornady Black at an advertised 2,750 fps and the 108-grain ELD-Match load at a stated 2,750 fps. Velocities were established from a 24-inch barrel.