There are some decent PE and cast Lewis guns out there, for use in detailing aircraft- Less frequent are good Vickers with fluted refrigeration jackets (although some PE sets bring good muzzle pieces for improving them). Recently I got a HR Models Nieuport 12 kits, and it brings some extra guns as optional armamtent, and there's an unusual Hotchkiss gun decently shaped. However, I'm not sure what would be needed to make it look as a ground-based weapon, as aviation guns were often alleviated of its refrigeration systems, wooden stocks, bipods, etc. D.
