Minishark

The Minishark is a machine gun that can be bought from the Arms Dealer. It costs 50 gold and uses musket balls or Meteor Shot. It has a speed of 'Insanely Fast' and deals 5 damage per shot not including ammunition used. It can be crafted into a Star Cannon

Here's a Demonstration of the Minishark.

When talking to the Arms Dealer, he reacts when you are staring at his Minishark, and tells you "You don't want to know how it was made".