The 6.8 SPC cartridge was developed due to troubling reports about failures of the 5.56 NATO cartridge to incapacitate enemy soldiers. During a development project led by a soldier of the 5th Special Forces Group and a member of the Army Marksmanship Unit, the goal was to create an enhanced rifle cartridge that was compatible with the M4 carbine—AR15—with minimal changes to the weapon. This started with the 6 mm PPC, which ironically is essentially the same cartridge as the recently released 6 mm ARC, but the project engineers necked it up to 6.5 mm. For some more irony, this is what is known today as the 6.5 Grendel. Due to the poor magazine capacity of this fatter case, it was discarded, and they went to work with the smaller diameter .30 Remington case. Ultimately what would emerge was the 6.8 (.277-caliber) SPC (Special Purpose Cartridge) which was submitted to SAAMI by Remington shortly after the turn of the century. Since its introduction there has been an ongoing argument as to whether the 6.8 SPC is a better combat or fighting cartridge than the 5.56 NATO/.223 Remington. It would appear the verdict is still out. Though used to some limited extent by military units, the 6.8 SPC never achieved widespread adoption by the U.S. military; the 5.56 NATO is still the primary chambering for individual military weapons. Given the press and publicity of the 6.8 SPC, civilians looking for a home/self-defense carbine now question which cartridge they should trust their life to.  [full article]