In a single action gun, the trigger's only function is to release the hammer. On a revolver, the hammer must be manually cocked each time. On a semi-automatic gun, the hammer must be cocked only for the first shot. The slide cocks the hammer for subsequent shots.

History

The single action was invented in the 1830s by Samuel Colt, and was put into production in 1836. Though the double action was developed in the early 1850s, the single action continued to be a popular gun. The Single Action Army, or Colt Peacemaker, became the quitessential sidearm of the West.