I love your list but I would switch out Bruno for Joe Colombo, perhaps you excluded him cause he didn't die immediately but in effect the outcome was the same and we're talking about a Boss being shot in the middle of Columbus Circle in broad daylight with all the immediate aftermath captured on film and the shooter being immediately executed as well. That was quick, clean and efficient. Whether it was Joey, Carlo or whoever else involved, it was done extremely well and even to this day we still don't really know who did it.

By your criteria I don't see how that can't make the list!