This weekend, I attended the largest machine gun shoot in the world, the Big Sandy MG shoot. I had loads of fun, and you can see some of the video here:
You know which gun this is. The "Chicago typewriter" of WWII. Features 2 removable 20-round mags. working safety and selector. fires from the open-bolt.
To use: disengage safety, select firing mode (default is SEMI), and fire with trigger or enter/return
This was actually the first gun I eve shot, at 12. My father owns one, (legally of a form 4 nfa item) and while quite fun, they are REALLY fast and heavy, not to mention expensive to feed.