Cynically, I wouldn't worry, as he probably won't be back if he got much sense of this tension from the "committee". From the HC standpoint, what's the line? It sounds like this one isn't far off from "correct". Steel mounted PA rifles, front sights that stick up 1", there's a whole list of things I find historically incorrect, but I don't care if someone else likes them. I think the real issue, if there is one, is whether it gives him a competitive advantage (maybe with roundball) and if so, is it against the rules as written? Why didn't they notice this detail at first? Is it worth fighting over? What good is going to come out of it? I certainly wouldn't find the guy out of line if he refused to modify a production gun that otherwise fits the rules. Let him shoot, and if it becomes obvious that he is winning because of this feature alone, look for a solution such as a handicap (or penalty). Personally I wouldn't do or say anything about it until he became comfortable in the group and only then if it became a real problem all of the time.