Its been a while since a played so i cant remember the names of things but i remember setting myself up with the first LMG you get, after a while i used the better handle or put the scope on it. i used the perk that increases accuracy whilst moving and when not aiming down the sights, and the stopping power perk i think.
it meant i could sprint around the map like a mad man spraying obscene amounts of ammo a great accuarcy.