hi fellow PM

PM player too here.

yeah, most SMG has no enough firepower, lots of it incapable of 1 hit KO. however PM are the most mobile, and the RoF of the SMG makes it perfect for ambush.
the idea is to not to have a front to front battle with RM. always bs and flank them. the odds are higher if we confront them face to face , especially fighting against cheating gun user (F2000, Mk3).
our battleground also has give advantage and disadvantage for us.SMG wielding PM excel very well at Escort and Cross Steal (as key carrier). as for Demo, its advisable to use Shotgun rather than SMG, due to the fact that most of the players here are Veterans, thus RM here has a higher Defense Rating (their skills increase DR and Helmet DR - can tank more damage). Shotgun also works seamlessly at Cross Steal (as defender) .
as for your problem, why adding RoF to a MP7? its RoF is good enough. you'll just make it spit more bullet uncontrollably. i recommend +accuracy, assuming you're headliner.
Laser Sight + SharpShooter Barrel + Stock Trigger (i know there is accuracy trigger there but it sacrifice stability) + Human Eng Grip.
this gun needs 3 headshot to kill, 2 to knock the helmet, 1 to kill. so it'll need 6-7 shots to kill a RM.