The original MARS (Mini Assault Rifle System) was based on a 5,56×30 round. The project started in 1997 when Colt was approached by Michael Harris of Special Analytical Services (SAS) with a concept of a mini-assault rifle that would have the purpose of being a personal defense weapon as well as have law enforcement and military applications His goal was to develop a weapon to replace 9mm pistols and submachine guns among the military, special police and security forces. The next step in taking advantage of the MARS system was to be the development of same-length larger caliber rounds for close range, rapid incapacitation situations. Before the project was shelved two rounds had been prototyped which, in test barrels, developed the high pressures required to potentially operate the mechanism. Both rounds are loaded on Starline *—* 10mm MAG brass. The 9mm round has just enough neck to hold the 124-grain bullet, thus maximizing powder capacity, and is loaded to the same overall length as the 5.56 round.