in Aunt Bee's Brief Encounter, he dis-assembles his shotgun after basically running off Mr. Wheeler.
There was one when Andy brought in some prisoners and locked them up. He had a shotgun and there were four prisoners, the Gordon boys who were operating a still. That's when Andy had a cast on his hand, broke a couple fingers in real life I think. Oh, its the ep when Otis goes to jail in Andy's house cuz theres no room in the jail.
It seems this question has morphed into a list of times Andy has fired or handled a gun so we can include the time he shoots Barney's gun at the ceiling in the courthouse in, 'The Gentleman Crook.' He also shot a rifle at the shooting gallery.
And to add to all of this: Andy used Gomer's box of light bulbs dumped from on high to make 2 crooks yell "Machine gun, he's got a machine gun!".