单动式陆军（Colt Single Action Army，简称：Colt SAA）是由柯尔特公司生产的一种单动式左轮手枪，此枪在西部片中极为闻名，更曾为美国最流行的轻武器之一（即使到了现在仍很受欢迎）。在1873年至1892年期间单动式陆军为美军的制式手枪，其炮兵型甚至在一次大战期间仍有出现。

单动式陆军有着「一把平定西部的枪」（The Gun That Won The West）的称号。

The Colt Single Action Army which is also known as the Single Action Army, SAA, Model P, Peacemaker, M1873, and Colt .45 is a single-action revolver with a revolving cylinder holding six metallic cartridges. It was designed for the U.S. government service revolver trials of 1872 by Colt's Patent Firearms Manufacturing Company – today's Colt's Manufacturing Company – and was adopted as the standard military service revolver until 1892.