Heavy weapons are a great addition to the single player, and provide some variation from standard weapons. In single player they are balanced, but that is not the case in multiplayer. From my experience, whoever can aquire heavy ammo dominates the match regardless of skill (that is until they run out of ammo.) I myself have won many gunfights that I shouldn't have, or lost to someone without having time to react, due to the power of heavy weapons. I know you tried to balance it out by making the ammo scarce, but the 60 rounds provided are enough to easily get 4-8 kills without even needing to try. I feel multiplayer would be much more balanced if heavy weapons in multiplayer were nerfed, or removed entirely.