Popularly called the "Humpback" due to the distinctive design of the receiver, this semi-automatic shotgun used a long recoil mechanism which was more commonly featured on automatic cannons.
An American design from 1898, it was the first mass-produced semi-automatic shotgun in the World. Versions of it were manufactured in the US and Belgium, and it was used as a trench clearing gun during WW1 alongside the more traditional pump-action shotguns. The 12G was a reliable, robust weapon which was produced from 1902 all the way up until the year 2000, and it has seen worldwide use by military, law enforcement and sports shooters.
- The Codex picture of 12G Automatic has no handguard or tube magazine.