Few points about why MG needs the buff, and how it should be balanced.
First: Mechs are not primary anti-infantry units by default so it makes no sense to use weapons that both weigh it down and affect only infantry. Such as small caliber machine guns. Thus, they carry only weaponry that can be classed anti armor, even though some of it is rlatively light stuff. They face mostly other Mechs and vehicles, if there's infantry support against them it's usually not the main threat, if it was you'd more likely send in apc's, tanks or other fighting vehicles with infantry support than risk ambush with your precious Mechs for insignificant foe.
Second: In a Mech that has mostly weapons that fire one shot every few seconds, any gun that shoots multiple projectiles per second and capable of killing humans is going to be classed anti-infantry because everything else sucks at it. It doesn't mean it isn't designed to hurt mechs.
Third: MG should be balanced around having 2-3 of them in a build, not as individual performer. 4 is rare and 1 is kinda stupid, in my opinion. I'm fine with either good damage (well, comparable to small laser) or devastating crit damage. Basically, if it doesn't hurt armor, it better rip apart the innards in matter of seconds when grouped. In other words 5 seconds for single machine gun tops, preferably firing a group of 4 in unarmored spot should rip it off in a second or less. Because it's not some man portable baby gun, it's a half ton monster designed to kill metal behemoths that happens to be good against humans too. It should have slightly higher dps than small laser because concentrated damage is pretty much always better than something you need to keep firing all the time.
Fourth: Mechwarrior has always had ablative armor, meaning that you could break it with a stick if you hit long enough. It has no damage resistance against weapons like real life hard armor, maybe in tabletop there's weapons that hurt only infantry but MG isn't one of them. If you insist MG shouldn't hit armor, then start applying it to the feebler autocannons too... Atlas front armor isn't going to be pierced by ac 2, 5 or maybe even 10. Certainly not by some shotgun ac 10 lbx. Similarly small lasers would heat it up a bit but I doubt they pack enough punch to actually melt it off.
Fifth: weapon definitions change, if they think that a 30mm gun isn't really much of a cannon and decide to call it a machine gun since it has high rate of fire it's not that unbelieveable. In Mech setting it certainly is small gun, if AC's start at 100mm like someone mentioned earlier.
Edited by Kirvesmies, 10 January 2013 - 04:48 PM.