even if you buff the LMG's, they still may be to cumbersome to actually be effective with in game.
But that's the point. They are supposed to be the weapons you use to take out groups of people at a distance. All three LMGs in CoD4 were incredible. The RPD was a low RoF, Low recoil gun that had no sway and with stopping power could two hit kill someone at any distance. The M249 had even less recoil and had a high rate of fire. It even would have SMG hipfire if you used steady aim and the grip attachment. The M60 was the gun that you didn't need stopping power for because at SMG range it did 50 damage per bullet. And the RPD and M60 could take out a helicopter with a single magazine.
The MW2 LMGs were okay, not as good as the CoD4 guns, but still viable, especially with the introduction of dual attachments. There were issues though, such as the assault rifles being too good at long range compared to LMGs and the silencers simply making the guns always take another bullet to get the kill rather than just make them have a mid-range dropoff.
In MW3 all of the LMGs have recoil that makes them a crapshoot at long ranges even with grip and kick and because of the dropoff you don't even do a decent amount of damage at long range. I will give IW credit though. They made it easy to take down air support with an LMG and blindeye.
Btw, has anyone done the hybrid scope glitch? A friend of mine showed me a way to make your character hold your gun weird using the a glitch the the hammer/hybrid scope.
http://www.youtube.com/watch?v=Ci1292UtyvM
The guy in video thinks you need a specific weapon to do the glitch but it pretty much works as long as you have sleight of hand and a a weapon with either the hammer scope or hybrid scope. It makes some funny positions and has a weird effect on the reloads.