Thats no Browning! The toggle lock mechanism on the side of the gun is found on all the Maxim clones: Vickers, MG 08 ... The shiny brass cooling jacket makes me believe, that this is a original produced by the Maxim Gun Company.
Then why are they even doing this!? Is it for a photo? Are they goofing around in their spare time? If the latter, why did they make a whole custom mount just for this?