Sounds like a lot of force would be applied by this tool. Would the bulge from overtightening by any chance be in the form of a ring at about the point where the threads meet the reinforce, the weakest point, as observed and not fully explained on a two or three No4's?.
If not, is it possible to recognise this "bulge" or other signs of overtightening that could stretch and fracture the chamber at the weakest point, and possibly go un-noticed?. What usually gives when you over-tighten?.