This model is in an indeterminate scale, and could be used with 15mm to 28mm figures.
On a sprue inside the hull are two pintle-mounted Gatling guns that can be mounted to protrude through the slot in the front of the hull — realistically, there would only be room for one there, with its gunner and loader and associated clutter, but I've provided two in case you want to make it look fiercer.
The main gun is a separate component (on a sprue) and can be installed at any angle you like.