Until either of those characters dies, then the whole party rapidly follows.
As for MGs - not looking at ROF specifically, but MGs in 4e are pretty weak using RAW. "More ammo" is essentially the one advantage they have, which has always felt wrong to me. I've played with house ruling it in a variety of ways (starting with reducing the default penalties for shooting them from -2/-3 to -1/-2, giving extra suppression dice chances, etc) but
this supplement (yes, it's a bit overpriced for what it is, but full of good stuff) has an optional rule that has solved the issue for me, I think.
Essentially it includes a "recoil limit" for every weapon, which if you exceed (in ammo dice) from an unsupported position gives you a -1 penalty. That's it. Too simple? Maybe, but I think it works fine for what it is. The recoil limit is typically 3 or 4 for assault rifles, and 2 for 7.62 battle rifles and MGs. An MG's bipod removes that penalty whenever deployed, letting you go full cyclic. Of course any other weapon with a bipod gets the same bonus, but those aren't super common. You can also remove the penalty by bracing your rifle, but that takes an action (and somewhere you could realistically brace it).
It's a nice easy rule that gets the job done and has tactical implications.