This is a really interesting piece with a mostly unknown origin. It was manufactured in the UK (the barrel was deemed Enfield-made by former Royal Armouries curator Herb Woodend) and is chambered for the .58 Morse centerfire cartridge. The date of production is unknown. It uses a gravity-feed magazine and fires via hand crank. Turning the crank cycles the bolt forward and back, not completely unlike a Maxim gun but without the automatic operation. It came out of a small Canadian museum in the 1950s, but its provenance before that is unknown.