Fast automatic weapons?

what is the fastest firing handheld automatic weapon (not pistols, cause thats the glock 18) with the largest clip? cause ther are some drum clips that go to 71 rounds, 100 rounds, 120 rounds, 150, 200, and 250. im not talking about stuff like the m-60. (even though thats a nice weapon) or mini-guns, cause you pretty much cant carry those. i mean stuff like the mp-40 and the AK-74 (even though thats a pretty slow firing weapon compared to other weapons)