I don't even open carry and I've run into nutjobs.
I was once eating breakfast in a Lakewood, OH McDonalds while doing my laundry when I encountered one.
As usual, I was wearing my NRA ballcap and carrying several Collector Grade books. An elderly cleaner started giving me crap about wearing an NRA ballcap, and declaring that the NRA should be BANNED. I noted that the last time people started banning organizations, we somehow misplaced 6,000,000 Jews. He responded that he wasn't sure that was such a bad thing.
In a "nut" shell you have the mindset of the anti-gunners.