Stronghold Miniatures makes/made the Beaverette in Mks I through IV, and a "Mk 5", which apparently has four .303 machineguns. They're from the former SDD range.
I don't guarantee whether he has these currently available, or is able to produce them, or whether you can get a response. I've had excellent service from him in the past, but the past few years have been very tough for him, and I don't know where things stand right now. Give it a try.
Here's a painted example:
http://www.ifelix.net/gamingblog/?p=6335Allen