IJunk turret might be a bad idea in a hallway, though I don't know how accurate it will be until we use it. In a tunnel you are likely to mine for a bit, go back, pick it up, bring it closer to the end and place it, then continue mining. Repeat as necessary. If you are mining a tunnel, and happen to be mining it slowly enough for the zombies to actually catch up to you, when they do break through, it will most likely be some place in between you and the turret. It will be facing your direction. That could be a problem.
