Have you ever heard of bending an Upper receiver?

[montana]

Many moons ago a friend of mine torqued his barrel nut as hard as he could with out using any grease, anti seize, or oil on his first Olympic arms build. Years later he removed his barrel and sections of the upper receiver threads pulled away. The barrel stud was fine as was the slot for the barrel stud on the upper receiver. I would have junked the upper at that moment but he decided to use it and mount another barrel on it. He doesn't shoot it a lot and uses it as a beat around pickup gun. I would never trust this upper and is the example why I would never purchase a Franken gun unless I knew the builder was competent.