Maybe some tweaks need to be done to the way LMGs work. I have a crazy idea.
LMGs should function completely differently from other weapons.
When not aiming down the sight...
They'll take time to get ready after you sprint (for 2 seconds you won't be able to shoot. Think of this like Red Orchestra Ostfront's MG mechanic but more forgiving)
There will be sway while you're hipfiring (which will make point shooting even harder)
There will be less recoil, but lots of sway, which is almost like recoil it itself because of how extreme it is.
When aiming down the sight while not using a bipod...
Instead of sway, there's sight misalignment, which is like sway with an antishake feature
When using the bipod...
Your mouse wheel is then used to fluidly adjust your stance like in Arma 3 or Escape from Tarkov.
(That way you won't feel like a sitting duck when you deploy that bipod)
The problem with a lot of these ideas is that you're doing arbitrary things to achieve arbitrary ideas of balance, when it's not necessary to do that.
Many problems with the LMG are caused by a lack of realism in the modeling that leads to problems.
The answer is not to tack on even more unrealistic behavior on the LMG with arbitrary restrictions, because then you've only compounded the problem by trying to solve one unrealistic aspect of LMG performance by creating a different aspect of unrealistic performance.
Ultimately the answer to weapons not performing realistically in game is to go back to the source and determine WHY weapons weren't used this way in reality and then think of way to model those reasons in the context of a game design.
It's far more interesting to the player, and more accurate, if you give them the ability to use an LMG in the full range of it's potential uses but with appropriate consequences for doing so. As opposed to just denying them the ability to experiment and use things in more varied ways because there's a preconceived idea about the "right" or "wrong" way to use an LMG.
Modeling how weight and balance impact weapons would already have some of the effects you want by:
- Slowing down their ability to transition between positions and slowing down their acceleration speed, and even slowing down overall movement and sprinting speed if the weapon is being held in the hands at the time.
- Heavier weapons take longer to bring up to sight.
- Heavier weapons take longer to swing around.
- Heavier weapons cause more fatigue when kept in the firing position, and have more aimsway as a result.
- Poorly balanced weapons and heavier weapons can be more difficult get and keep on target from a shoulder fired position, despite the fact that their increased weight reduces recoil. Being unbalanced can also effect the way the weapons recoil.
- Overall fatigue from actions will increase faster.
Maybe instead of using large magazines, you'll just use ammo belts and you'll have to manage heat. (and get additional ammo belts from teammates like in Darkest hour)
That means MG guys have low ammo by themselves but can be a constantly refilling machine if teammates go to them and press ACTION to give them ammo.
When they do that an animation of the soldier giving you an ammo belt plays. He presses F, then you press F to accept ammo. You have to wait 2 minutes before you can give ammo again. If the MG overheats, he gets 1 barrel change, after that it's a broken gun. Supressors can be equipped but they melt and on night maps they glow bright.
That's a viable idea. But you have to remember that it is possible to carry more than one belt into combat, and some soldiers have done it.
So the proper way to model this is not with arbitrary restrictions like saying "no more than one belt for you, SAW gunner".
Instead, the proper way to deal with this is to effectively model the impact that extra weight and bulk have on the performance of a soldier. Give that SAW gunner a reason to not want to have to carry all his own ammo if he doesn't have to. The same kinds of reasons they don't want to have to carry it all in reality. It impedes their performance and endurance.