Looper's "futuristic" Blunderbuss shotgun is a truly bizarre weapon. Looper is an action thriller that revolves around Joe (Joseph Gordon-Levitt), an assassin responsible for killing victims sent back through time from 2074. This type of hitman is known as a "Looper," as one day Joe will have to kill his older self to close his own "loop" contract. This becomes complicated when his older self - played by Bruce Willis - is sent back to be killed and manages to escape. This makes both young and old versions of Joe a target for the crime syndicate, with Willis' Joe set on bloody revenge against those who wronged him.
Looper became a surprise success in 2012, thanks to its great cast, dark storyline and unique time-travel premise. Outside of the make-up applied to Joseph Gordon-Levitt to make him resemble Bruce Willis being somewhat distracting, Looper received great reviews. Off the strength of the film's success, Rian Johnson would later be hired to write and direct Star Wars: The Last Jedi in 2014.
The bulk of Looper takes place in 2044 but the film very much takes place in a retro-futuristic world. Most of the assassins in the film wield oversized revolvers instead of automatics, while the Loopers themselves are armed with an oversized Blunderbuss during their assassinations. This weapon is an update of a one-shot shotgun from the 18th century, but unlike the original weapon, the Looper version is capable of firing multiple rounds at a time. By design, this weapon is rather lo-fi and functional, having been created with a sole purpose in mind.
The Looper Blunderbuss is used for assassinations because of it's wide-spread, meaning it's near impossible for a shooter to miss at close range. This has the drawback of making the Blunderbuss fairly useless at a distance, however, and it's poorly suited for a prolonged gunfight. While's neither pretty nor glamorous, the Looper Blunderbuss quickly became an iconic weapon from the movie, being prominently featured on posters and artwork.
The Looper Blunderbuss also symbolizes the film's stripped-down approach to technology, with the future of 2044 - or the brief glimpses of 2074 - not looking all that different from the present day. In addition to being a smart way to keep costs down, it helps give Looper the feel of a Western, especially in the final showdown between young and old Joe. Ironically, this is where young Joe's Blunderbuss comes in useful for stopping his future self - just not in the way he imagined.