I think we should have a mounted machine gun.
Similar the M1919 Browning .30 used in Day of Defeat but with similar firing speed, model, half of the damage of the rifle, less accurate and the maximum degrees of which it can be turned once set up.

BEFORE YOU LOSE YOUR SHIT AND START RAGING AT ME WITH HERPS AND DERPS, KEEP READING.

I know this idea has been done to death, but every time I've seen it I can see problems arising everywhere, but I think I've solved them all.
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The machine gun should take 5 seconds to set up, can only be set up with a wall 1 block higher than where the player is standing, take 5 seconds to pack up, and make it so when it's set up, you have to wait 60 seconds before taking it down to make it less overpowered.

EDIT: It also doesn't damage blocks, preventing Deuce and his best mate Deuce, from tearing up an entire structure.

It should have an ammunition supply of 300 bullets (sounds like a lot but at 500 rounds per minute, it goes faaaaaaaaast.

EDIT: Once out of ammo, the gun disappears and spawns ten minutes later back at your team's tent.
If left for too long without being used, say five minute, It spawns at the tent.
This prevents Deuce from taking the gun, digging a hole somewhere, plugging the hole and suiciding with the gun still in his hole, never to be seen again.

To make it even more balanced, and to promote teamwork, it should have one person aiming the gun, and another person firing it.

I.e the first person to go to the machine gun once it's set up and use it (press E) - is the Aimer, the second will be the Shooter, as this stops people from just racing to it and having it be first in first serve, people have to actually think about how they're going to go about this, and who does that.

The Shooter should be able to see what the Aimer is looking at with a small screen that pops up near the center bottom of the regular screen.
Kills that are caused by the machine gun team should be awarded with 0.5/1 point(s) to both the Aimer and the Shooter.

There should be a maximum of 1 of these machine guns per team, and it should spawn near each team's supply tent.

The gun would also have to be destructible/capture-able when unmanned.

I.e the greens have a nest set up overlooking a valley between two mountains. (inb4 titfuck joke)
The blues are getting slaughtered as they walk past it, so two blue guys decide to flank it.
Due to the inability to turn more than say 70 degrees once set up, and the 5 second pack up time, once the green guys know the blues are descending upon them, it's all too late.
Both the green Aimer and Shooter are killed in the attack.
NOW.
The two blue guys can either decide to capture the machine gun and turn it on the greens, or skip the effort and just blow it up with ~ten bullets.

I apologize for the essay above, but really to make it non-ridiculous and keep the realism and fun, I had to do a lot of thinking, reasoning and problem solving and mainly typing.

Tl;dr? FUCK YOU, READ IT.

^no, i didn't. Just one guy is okay.

That would mean some Deuce retard could take it and run off by himself to the enemy base, set it up thinking he's good and get absolutely massacred, essentially giving the enemy the gun.
Also it's less fun and means less teamwork, two people is more fun anyway.

so basically there's no reason to use it at all ever

What part of it isn't useful?
The superior firepower?
The superior fire speeds?
Both its defensive and offensive capabilities?
The potential of superduper funtime?
The ability to give help people to take on an unbalanced enemy team?

Loki kind of nailed it.

Also, most of the machine gun suggestions that I have seen nurf its usefulness. Especially when it comes to accuracy. Obviously, making it as accurate as the standard rifle would be ridiculous, but it should at least be as accurate as a hip-fired rifle.

-The superior firepower?
"half of the damage of the rifle"

-The superior fire speeds?
"less accurate and the maximum degrees of which it can be turned once set up."

-Both its defensive and offensive capabilities?
you only get one, and it has to be used by two people, and you can't move it easily.

-help people to take on an unbalanced enemy team?
if the teams are unbalanced it's getting taken from you, assuming they even want it

the rifle is better in every situation

A .9mm hollow-point is bigger and would do more to a person than a 7.62 used by the AK-47, yet the AK-47 has much more firepower due to the amount of lead it can fling at someone in a very short amount of time.
The firepower from this MG would be from the 500 odd rounds per minute you're shooting at people, which would do much much much more damage overall than the rifle.

What does the accuracy and mobility of it have to do with fire speed?

A well placed MG with a good team can absolutely fuck ten people running at them...

"A well placed MG with a good team can absolutely fuck ten people running at them..."

Well yeah, if they're not trying to shoot you. Two blocks stacked vertically is hard counter to this gun.

I'll explain what I would do in a little story:
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<Random Tard>: kaputnik come help with mg pl0x
<Mr.Awsome>: Okay, where to?
<Random Tard>: dat mpuntan over ther
<Mr.Awsome>: Here?
<Random Tard>: yess we will detroy them
<Random Tardagain>: o no te green nubs are cummin
*Random Tard prepares to load the mg but is stuck because nobody is firing*
<Mr.Awsome>: Trololololololololololololololololololololololololololololololololololololol nub
*Random Tard dies, rages around, gets spawnkilled 5 times, rages more, rage quit*
*green nubs use the mg to do a teamkill massacre*
*Random Tard leaves*
*Mr.Awsome leaves*
*green nub 1,2,3,4,5,6,7,8,9,10 over 9000 leaves*
*blue awsome army start teamkill massacre*
*everyone leaves*
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@loki
That's irrelevant.
I already said it doesn't break blocks.
In order to be any threat to the MG crew, they'd have to expose themselves to it.
Ten people hiding behind a wall is a lovely time for an ally with a couple of grenades, even then if they ever came out from behind the wall and just ran at the gun, they'd probably be obliterated unless they got very lucky or actually had some sort of plan to get behind it.
The entire reason I set all of these is so that it has the potential to be amazing at defending a certain spot, but also not totally impossible to stop like the other suggestions I've seen.
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@kaputnik
That's the most retarded thing I've ever seen on this forum.
You don't understand how teamkilling works in this game... Do you?

@Master Yeah I know.
One man is enough.

"A .9mm hollow-point is bigger and would do more to a person than a 7.62 used by the AK-47"

1.) Wrong. Even with the expansion of the hollow-point round, the 7.62x39 packs much more kinetic energy but is also "soft" enough to ricochet off of bones.

2.) An AK-47 has vastly superior accuracy and firepower at much greater ranges than a nine millimeter.

It seems like these machine guns that everyone is proposing would only be efficient if the enemy is standing 5 feet away from you. Any farther than that and the person manning the machine gun would get their face sniped off.

If two people go off with the MG, people will WANT to do the firing and will follow in order to try and either fire it or help guard it, if nobody fires it, the guy carrying the MG who set it up, can always carry it back to base and let somebody else use it, or just bail and use his rifle like everyone else.
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As you said before Galaxy, "it should at least be as accurate as a hip-fired rifle."
That's a brilliant suggestion and had my edit function not fucked up, would be in the main post.
As for this: 1.) Wrong. Even with the expansion of the hollow-point round, the 7.62x39 packs much more kinetic energy but is also "soft" enough to ricochet off of bones.

The 7.62 would just go through a person, .9mm hollowpoint are designed to use almost all of their energy inside a person and stay in the body in order to not kill anyone behind them.
The .9mm would create a much bigger hole to bleed out from.
The 7.62 has MUUUUUUUUUCH more kinetic energy, and if it hit a bone it would absolutely fuck it up, but shooting at center mass, there are much more vital organs than bone, and that's how you fuck someone up.

Also, I wasn't comparing accuracy... the fuck?

why cant we just get a COLT 1911....or COLT 1912 Springfield Armory

Pistol or massive machine gun.
Tough one.

"In order to be any threat to the MG crew, they'd have to expose themselves to it."

Yeah they would have to move a few inches to the side and headshot either of the immobile targets.

"Ten people hiding behind a wall is a lovely time for an ally with a couple of grenades"

Double click your mouse, that's how long it would take somebody to kill both operators. They would never need to hide.

"then if they ever came out from behind the wall and just ran at the gun, they'd probably be obliterated unless they got very lucky or actually had some sort of plan to get behind it."

Yes and they'd be obliterated if they all ran onto the same block where you threw a grenade. Unfortunately the other team often does not consist of lemmings.