I used to be associated with a wealthy machine gun collector and class III dealer, and would go shooting, on occasion, with him and his friends. Ammo was not an issue as he provided it all. I shot a lot of machine guns, but the one I really enjoyed the most shot .22 LR. It was easily controlled and shot at some amazing rate of fire. (Sorry, I don't remember what gun it was, it was a long time ago)
I also enjoyed the cheap, but reliable Sten. For a pure testosterone rush, it is hard to beat a Thompson. We all have a bit of gangster in us, and it is fun to let out every now and then. Shooting the .50 cal. is something neat to brag about later, but it was not nearly the fun as a hand-held SMG.
I am glad that I got to get the machine gun thing out of my system. As a working stiff, I could not afford to purchase or feed machine guns. A fun day at the range with one of these types of weapons could easily cost me a months wages.