Cooper observed that one of his competitors, Jack Weaver, used a peculiar shooting stance that enabled Weaver to fire his double-action revolver surprisingly fast-yet accurately. (Weaver was one of the few wheelgunners in the League; most favored the M1911.) Cooper digested Weaver's stance of a bent elbow on the support arm and refined it for the 1911. He named it the Weaver Stance and advocated it above any other technique when he later became a full-time shooting instructor. That development came in 1976 when Cooper founded Gunsite, a ranch in northern Arizona dedicated to propagating the full body of knowledge he had, by now, codified as the "Modern Technique," based largely on what he'd learned at those Big Bear "leather slaps." Simple to describe yet multi-faceted in its nuances, the Modern Technique begins with four rules of safe gun handling. We've all seen these very same rules, in precisely the wording Cooper originally articulated, displayed on signs in police shooting ranges, military ranges, civilian ranges, gun shops and even on business cards. Every gun owner should commit them to memory: Rule One: All guns are always loaded. Rule Two: Never let the muzzle cover anything which you are not willing to destroy. Rule Three: Keep your finger off the trigger until your sights are on the target. Rule Four: Always be sure of your target.
John Dean "Jeff" Cooper was recognized as the father of what is commonly known as the Modern Technique of handgun shooting, and one of the 20th century's foremost international experts on the use and history of small arms.
Cooper was commissioned into the United States Marine Corps prior to the attack on Pearl Harbor. During World War II he served in the Pacific on the USS Pennsylvania (BB-38), and then was recalled to active duty for the Korean War, resigning his commission as Lieutenant Colonel in 1956. He received a bachelor's degree in political science from Stanford University and, in the mid-1960s, a master's degree in history from the University of California, Riverside.
In 1976, Cooper founded the American Pistol Institute (API) in Paulden, Arizona (later the Gunsite Training Center). Cooper began teaching shotgun and rifle classes to law enforcement and military personnel as well as civilians and did on-site training for individuals and groups from around the world.
Cooper died at his home on the afternoon of Monday, September 25, 2006 at the age of 86