This violent-looking device is actually an innocent and rare camera designed by Leica.
A company called Tamarkin are auctioning it in a sale of collectible cameras. Called the Leica Gun, it's fitted with a 400mm Telyt lens, and has the code RIFLE on it.
Apparently meant to be mounted to a tripod, the design apparently ensured a super steady shot. It's also possible that they were designed to be mounted to airplane wingtips during WWII.