1873 Single-Action Cattleman 12-Shot In 1873, Colt&';s single-action Army (SAA) revolver became the Army&';s standard sidearm. Cavalry troopers were armed with the new revolvers. Lawmen and outlaws alike were quick to adopt the handy new 6-shooter which earned the nickname "Peacemaker." Specifications Caliber or Gauge .22 LR Barrel length (Inches) 5.5" Chamber (Inches) - Choke - Product Type Revolvers