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Would a rapid-fire weapon with a small shield mounted to it be a possible addition to the pack? A perk could be that it has LOTS of ammo, and fires at a decent and accurate rate, but is very weak, and slows down players carrying it.
why would it need a shield
furthermore i think you've given me an interesting idea for the LMG: by itself, you can't fire it, but if you click you put it on a post and erect it in the ground, and use it to deny areas much like a sentry gun
catch is that it takes no damage and it's very easy to be shot right through it- the only way to remove it is to walk up to it and activate it, unrooting it from the ground and just turning it back into a normal item