We visually looked at firing pin protrusion. It looked similar to my vintage guns, but we didn't measure it. I have Kuhnhausen, so we knew what to look for. But he left with his AO before we could go farther with exam. We also got light primer strikes with American Eagle factory, in the AO, which shot fine in the Underwood. Maybe it is a weak hammer spring, but in a new gum? I relayed the knowledge you provided. He is going to take it to a gun smith.