In 1846, when war with Mexico was looming and Sam Walker's Mounted Rifles needed powerful handguns for action on horseback, Walker ordered 1,000 improved Colt revolvers. The Walker model held 60 grains of black powder and chambered six, .44-caliber balls. The massive fire-power needed a much stronger frame and a larger design than earlier models. The Walkers were 15-3/4" long and weighed nearly four and a half pounds. The reputation of the formidable Walker black powder firearms ensured Colt's success.