I felt the need to check this timing myself, and had different results to
you !
I used a ‘quality’ stopwatch for timing the time taken to fire 30 rounds
for both the mp40 & thompson in ET & vanilla RtCW… these are my
results: (Note I fired 2 shots from the mp40 in RtCW, so the clip
contained 30 rounds before commencing the timing)
RtCW:
MP40 - 3.5 seconds = 515 rounds per minute
Thompson - 4 seconds = 450 rounds per minute
ET:
MP40 - 5 seconds = 360 rounds per minute
Thompson - 5 seconds = 360 rounds per minute
Obviously the times may be slightly out, as its impossible to be 100%
accurate, but I believe these results to be accurate enough for
comparison.
Now, I personally don’t really care what the firing rate is (within reason),
as long as everyone is the same = fair.
Having said that though, a slower firing rate does mean you need to be
more accurate, which suits me fine 
Hewster
