The Sjogren Inertia Semi-Automatic Shotgun,
One of the first semi-automatic shotguns invented, the unique Sjogren was the creation of Swedish inventor Carl Axel Theodor Sjogren. Unlike most if not all other longarms, the Sjogren used what is essentially a recoil operated slide, like on a modern semi-automatic pistol. When fired, recoil from the discharge would force the slide back, which traveled on a set of rails. When the slide was forced back, the empty shell was ejected and a new shell was loaded from its five round tubular magazine.
Originally the Sjogren was designed as a .30 caliber military rifle, and submitted to the British Army as well as other militaries. All rejected the design, seeing it as too complex, as well as too costly. Without being able to secure a military contract, Sjogren focused on producing shotguns using his inertia system. Between 1908 and 1909 around 5,000 Sjogren shotguns were produced by the Danish firm Haandvaabenverksäderna. Unfortunately the design never took off, mostly due to price, as the Sjogren cost substantially more than the common double barrel or pump action shotgun.