That's a great idea. I think that it would really increase the amount of teamwork. The weapon would have a lot of power but you are also vulnerable if you are camping alone with this gun.
The ideal tactic would be to have your squad protect you to the point where you set up the gun. Then the squad deploys in various fields of fire along this "kill zone" and wait for the enemy.

The ammo must however be limited to like 200 rounds per belt and like 3 or 4 belts so people don't just blast away indefinetly.

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