I've fired an Uzi and that was pretty cool. The recoil on full tilt felt more like a giant, high pressure squirt gun. It didn't beat on you like an AK on full auto - just a constant upward pressure as long as you held the trigger in.
My (Bucket List) desire is to fire an H&K MP5, an FN P90, a Schmeisser MP-40, an 1870's Gatling gun and a Barrett M82 before I leave this rock in my pine box. Clicking off some rounds with a Browning M1919 or similar model would be great too. If I ever make it to the Knob Creek machine gun shoot and can buddy up to the right people, I should be able to sample some of those.