Also having used LMGs a lot, I have to agree with COD_Widow.
The trick to LMGs is NOT run & gun. The trick to them is to go prone. You can make an LMG work on any map, but there are a couple of maps where they shine really bright.
I like ANY LMG with Blind Eye, Assassin, and Marksman. All you need to know is +/- 2 feet of the target. If you know that, and with Marksman you will, you will get a kill - even with a Silencer.
The M60 benefits from any and every attachment you put on it, but what you use really depends on how smart the opposing team is. In any case, the best proficiency is the Attachment proficiency - even though the 60 kicks like horse in heat. Grip helps with this problem and so does the silencer. The biggest problem I run into with the M60 is the stock iron sights. You can still work magic with the gun using the iron sights, but you have to scan non-stop or else someone is going to edge into your peripheral vision and you won't know it. Ideally I like the M60 with a Red Dot Sight and Extended Mags, but it depends upon how sharp the opposing team is. If they are smart, then I first try switching the Ext Mags for a Silencer. If that doesn't work, I exchange the RDS for a Grip. That usually solves all the problems. You can get deeper; sometime using Kick and a Silencer works, sometimes Kick and the Grip works better. Just depends on how your opponents are reacting.
As for the other LMGs, any combination of attachments works fine. Ideally I like Grip and a Silencer. If you are prone, Attachment proficiency is the way to go. And a prone LMG beats a mobile LMG all week long.
Of course, in order to make this class work, you have to get beyond the camper vs rusher thing. Different situations call for different tactics. I do both at different times so I have no problem with anyone else that does one or the other.
