Run, one of Murphy's Military Laws is that your weapon will always be built by the lowest bidder.
The MP40 has been changed for .65 and for the better. It is pretty much the way it should be. Thompsons always have been a pain and have way, way too much accuracy. The only complaint I have with Psshs are that you can run and gun with them, particularly in the Berlin map where this is extremely noticable.
I don't know if greaseguns are codwed the same way as the Thompson but if they are that's a problem.
Again, the MP40 is fine.