I'd worry the impact gun might crack a ceramic lining. I had no problem with ours, but I used the cargo strap and 2x4 against my hip technique. I also used a dab of 3M PTFE sealer on the new one. It won't stop the head from grounding to the tank case. Naw, it isn't getting in our drinking water either. Just put it on the upper 2/3s of the threads will be enough to keep it from rusting all the way and won't leak into the tank.