I have an older 10 gauge with a 34" barrel that got stored in a damp environment for several years. After cleaning it up, all of it looks perfect except for some pitting around the the firing pin area, some of which was 1/16' deep. I blasted the receiver, ultrasonic cleaned it, and welded up the pits with a TIG welder, then faced it back flat and polished. I am going to recoat it with a baked on teflon/moly finish. I want the gap to be right. What is the limit to the gap on a 10 gauge NEF? It still fits very tightly.