Frizzle said:
Instead of overheating, I think they should make MG's and other heavier weapons slower to target with. Meaning you can't turn as fast, or put the sights on your target as quickly. They should also have momentum. You swing 90 degrees with your heavy gun, and the sights slide past the target before coming back to where you wanted to aim. That's realistic. Also, movement should be slowed. Someone can sprint for a long way with a pistole, but with a MG? haha not very far at all....
Exactly.
Here is an assault configuration (only 100rd belt case) LMG being worn.
http://upload.wikimedia.org/wikipedia/commons/1/1c/Hungarian_soldier.JPEG
Even with the reduced amount of ammo, it weighs around 10kg. Try holding up 10kg with two hands at arm's length (steady, as if you were aiming) and see how long you can do so. A soldier will, of course, have at least 15kg more on his body at the same time.
In short, a LMG cannot be used accurately (with sights) in combat for any duration of time while moving or standing upright.
The right way to balance a LMG is not to make it another assault rifle, but to make it semi-useless while moving, and a total murder machine once prone and stationary. It's a tactical support weapon. Its user should be dependent on his teammates for protection while on the move, as well as for covering the flanks and rear once the LMG is in position. The payoff is that once you are set up, you completely dominate your chosen fire sector, which lets your teammates to move in better positions and so on.
Like Canebrake said, there's nothing realistic about a LMG jamming in a game due to overheating.
Here's a regular assault rifle firing 300 rounds, something it's fully capable of by design (although it's a safe bet that the weapon's accuracy is permanently affected at the point where even its handguard catches fire).
http://www.youtube.com/watch?v=eNAohtjG14c
For a LMG, 300 rounds is more of an appetizer than a challenge. They are machines designed to keep on churning out bullets without interruption.