One of American gunsmith John Moses Browning's most famous designs (and one of the most popular shotguns of all time) was the Browning "Auto-5". The Auto-5 appeared as the world's first truly successful semi-automatic shotgun, proving hugely popular the world over. Production of the firearm spanned the world - from Europe to the United States and ultimately Japan - covering nearly 100 years of non-stop manufacture. The weapon featured prominently in actions involving World War 1, World War 2, the Korean War and the Vietnam War where its short-ranged lethality could be put to good use.
Design work on the Auto-5 began in 1898 to which Browning secured a patent for his "autoloading" design the following year. The action (known as "long-recoil") depended on the temporarily joined bolt-and-barrel recoiling backwards in unison to help re-cock the hammer for subsequent firing. It was during this action that any spent shell casings were ejected, for the barrel returned forward sans the bolt. With the bolt eventually moving to its original position, a fresh shell was introduced from the awaiting tubular magazine - the weapon then made ready to fire again. This configuration now allowed shooters to fire off all shells in the magazine within seconds. A key quality to this semi-automatic autoloading feature was no dependence on a manually-actuated pump-action slide facility.
Having worked previously through the Winchester Repeating Arms company, Browning brought his new design to the company under new terms. After an agreement with Winchester failed to materialize, Browning took his work to competitor Remington Arms Company. however, fate intervened at this time with the death of the company president, forcing Browning to look elsewhere for the interim. He found a taker in the Belgian concern of Fabrique National (FN) and production ramped up in 1902. Browning then finally netted an agreement through Remington for stateside production in 1905, these marketed under the Remington Model 11 product label.
FN production spanned from 1903 until 1939, covering World War 1 and the beginnings of World War 2. When the German invasion of Europe at hand, production of the Auto-5 in Europe was stopped and relocated to the United States through Remington Arms, the Auto-5 produced concurrently alongside their Model 11. Remington production of Auto-5 guns spanned 1940 to 1946. Savage Arms also took in production of the Auto-5 from 1930 to 1949 and delivered these under the Model 720 and Model 745 names. When the dust over Europe had finally settled with the end of the war in 1945, FN resumed production of the Auto-5 in 1952, this continuing until 1976. In 1975, B.C. Miroku of Japan the undertook production of the Auto-5 under license, bringing about an end to its run when the final forms were completed in 1999. The last of the original Auto-5 shotguns were shipped out in 2000.
Auto-5s lived a good long healthy service life with the American military, ultimately seeing the end of its fighting days in the Vietnam War. In all, over 2.7 million Browning Auto-5 shotguns were produced worldwide, favored by many soldiers, security personnel, law enforcement, sport shooters and casual shooters alike for its base firepower, inherent reliability and in-the-field robustness.
The Auto-5 was formally known as the "Browning Automatic 5". Browning himself though highly of this particular design, recognizing it as one of his finest achievements in the field of firearms. Due to the distinct design of the receiver, Auto-5s were also known as "Humpbacks".
In 2012, Browning released a new, revised Auto-5 line with a simpler action involving a "short-recoil" (inertia-type) system to continue the famous Auto-5 legacy. The revised form is different enough from the original that parts are not interchangeable between old and new Auto-5s according to Browning. The revision was necessitated by the high production costs related to original Auto-5s.