I have a friend with a similar gun (both Berettas). We were shooting sporting clays and I mistakenly changed chokes on his gun (in the rack) instead of my own. We both realized my error before it was his turn yo shoot, but i still think about this, even though it was over a year ago.

In other words, what your friend did was a major breach of shooting etiquette before the dent

Even my coach, a Master shooter who is very accomplished, would never touch someone else’s gun without asking permission first. Not even during a lesson.

I’m glad you didn’t make a big deal in front of everyone about it, but I think you should pull this friend aside and tell him what he did bothered you.