"Many progun folks were negative in attitude but changed their views"
I'm with that.
In my childhood I used to think the only folks that needed guns were drug dealers and cowboys.
Then my freshman college roommate took me out shooting with his Glock. He and a few other old hands at the range ended up in a ceaseless (friendly) trash-talking war about the others' inability to hit the water if they fell out of a boat.
I was hooked. I had never realized how shooting was a sport, a past time, something that could actually unite people instead of just kill them.
Anyway, take your buddy out plinking. Make it a point to shoot the bull with other folks there. If he's still an anti after that, so be it.
Proverb for Paranoids: The innocence of the Creatures is in inverse proportion to the immorality of the Master. -T. Pynchon