Actually the M1 Tommy gun had a ratio of fire between 600-700 rounds per minute.
The Mp 40 and the Sten down at 500 rounds per minute.
But the PPSh-41 and the Suomi have 900 rounds per miute.

Earlier Tommyguns had a higher rate of fire, but there were a lot of modefications done to make it cheaper to produce, and easier to operate. (grunts ain't geniouses you know)

__________________
'We march. The enemy is retreating in transport. We follow on foot.' Lt.Neil McCallum 5/7 Gordons 19th November 1942