Hornady

Hornady Black Ammo 6MM ARC 105GR BTHP Match Black Rounds per Box - 20 The 6mm ARC is unique among rifle cartridges in that it fits in an AR-15-pattern action, functions reliably out of standard-capacity 24- or 17-round magazines, and remains supersonic beyond 1,000 yards in a standard atmosphere. The 6mm ARC is based on the 6.5 Grendel. Hornady started by necking down the cartridge to 6mm and then pulled the shoulder back closer to the case head .030-inch. Engineers also shortened the case to make the cartridge friendly to long low-drag bullets that have high ballistic coefficients. The 6mm ARC was designed around optimal use with a 108-grain bullet.