Porking the weapons to try and prevent Rambo's is not the way forward, if you provide enough realism, the players will have to use the guns like they should be used, thats what should be strived for!
Thats just not happening right now, i've spend countless houers trying to practice with them, and the logical outcome was: dont even think about using them like a real soldier would, its just not effective, it doesen't get you kills, just spray and prey from the hip!
Sorry, but the way to code an SMG is to mimmick a real one, they dont have much recoil, they are easy to control in short bursts, even if they do have a high rate of fire, but the pistol round is its downfall at range, that is where you must put the coding effort!
Its not hard, give the projectiles a timer, the more time passes the worse the accuracy gets, thats what happens in real life, as the projectile looses velocity, and the spin induced by the rifling slows, the projectile gets more inaccurate.. same thing happen for rifles, just slower as the velocity and momentum involved is so much higher.
Ofcourse it should still have x amount of recoil per shot (but less than half of what it is), thats real, thats why 3 round bursts = good, and holding down the trigger = bad, but that 3 round burst should hit a man sized target within a range of 20-30 meters or so fiering carefully aimed whilst crouching.
What i'd really like to see recoil-wise is a non-liniar recoil, so instead of applying a hard recoil from the get go (think 50,50,50,50,50), the weapon would get harder to controll the longer you fire it (think 10,10,15,20,25,30), that would be pretty easy to code, and would mimick what really happens very well, controling that short burst is not the problem, its when you let'er rip it goes wrong, its hard to explain, but its like your getting slapped about, and the longer it continues the harder it is to keep your aim.
What you'd get then is an SMG clouse to real, devestating at clouse range if used well (bursts, aimed), but not very reliable at longer range (inaccurate, and bullet drop), and then we'd finally have the room-clearing and peremiter-securing weapons that they should be.
And mind you, im only talking about aimed shots here, please keep the wild recoil in hip mode! so people will stop using it like the Rambo gun it is right now! and they will, once its actually worthwhile to aim them, thats what people will do in all but emergencies.