John Dean “Jeff” Cooper (1920-2006) was a United States Marine, the creator of the “modern technique” of handgun shooting, and an expert on the use and history of small arms. Born on May 10, 1920 in Los Angeles, California, Jeff Cooper graduated from Stanford University with a bachelor’s degree in political science. He received a regular commission in the United States Marine Corps (USMC) in September 1941. During World War II he served in the Pacific theatre on the USS Pennsylvania. By the end of the war he had been promoted to major. He resigned his commission in 1949, but returned to active duty during the Korean War, where he was involved in irregular warfare, and was promoted to lieutenant colonel. In the mid-1960s, he received a master’s degree in history from the University of California, Riverside. From the late 1950s through the early 1970s, he was a part-time high school and community college history teacher. In 1976, Cooper founded the American Pistol Institute (API) in Paulden, Arizona (later the Gunsite Academy). Cooper began teaching shotgun and rifle classes to both law enforcement and military personnel, as well as civilians, and did on-site training for individuals and groups from around the world. He sold the firm in 1992, but continued living on the Paulden ranch. He was known for his advocacy of large caliber handguns, especially the Colt 1911 and the.45 ACP cartridge. Cooper was married to his wife Janelle for 64 years. They had three daughters. He died at his home on September 25, 2006, at the age of 86.