M45A1 is based on the original M1911 design by John Browning, and has been the standard-issue side arm for the Force Recon Element of the United States Marine Corps' Marine Expeditionary Units since 1985. In the late 1980s, USMC Colonel Robert Young laid out a series of specifications and improvements to make Browning's design ready for 21st century combat, many of which have been included in MEU(SOC) pistol designs.