This is the Handcannon from Bioshock Infinite.
I couldn't find any .stl's of the model so I decided to tackle the project and I'm very happy with how it turned out.
This is a static prop and has no moving parts beside the cylinder and hammer. The gun does not open up as it does in the game because the in game model is an innaccurate representation of the real life model of the colt navy.
Grips and Barrel are connected with pegs, and the posts act as the pivot for most of the parts. The "Pivot Post/Pivot post cap" .stl's are what makes the barrel swing in accordance to the grip section. The "Loading post/Loading post cam" Is the end part of the barrel where the rear sight of a pistol can normally be found.
Again make sure to sand connecting parts just in case to get the perfect fit.