I'm guessing it will be similar to the sentry gun.
I think it will be a KS, it will die if someone knifes it or if it takes too much damage.
And it will die by itself after a period of time.
Sentry Guns aren't overpowered, and they shoot every thing in sight, they don't just let you see if someone is coming. Besides the only thing the enemy loses if you use this, is the element of surprise. The enemy could have a better weapon, more accuracy, or something like that.