Harry, there should be no problem with the FPS out of the box. The last time I chrono'd mine, it was doing about 313 FPS, which is pretty typical. And for a short-barrelled gun, they have very good range and accuracy. (It's only the very early ones that were substandard.)
You've got nothing to ein, zwei, drei, vier
You wont be dissapointed Matt 
out of the box mp40`s are fine mate, i love them as a gun . 
ive had three , and all have been great, not the best fps or rate of fire, but fine guns none the less
"Take that you rotton helping of strawberry flan!"
Joseph Porta to "strawberrys and cream", in the sven hassel book ,ogpu prison
I got the gearbox cleaned up and re-shimmed, it shoots a touch below 340 with .2s. Not upgraded a single part and I've no need to with the range it gets.
Friends meet to part - love laughs at faith;
True foes, once met, are joined 'til death!
