It was a bit wilder than that!
First, the gun was an Italian replica 1875 Remmie with a 7.5" tube. OPEN CARRY!
The goblin fired as you said, lightly wounding the clerk, good guy with the Remmie drew, fired and hit the goblin who didn't go down, good guy dove behind a plastic barrel full of ice and soda as cover. On impact with the ground, good guy somehow damaged the trigger on the Remmie clone. BUT he still kept in the fight, slip-hammering and firing it with the thumb. An extended gunfight broke out that way, good guy fired a total of four shots, hit with three including the first, bad guy ran his gun dry without any more hits on anybody. On at least one occasion goblin pointed his gun at somebody else, good guy saw it, fired to put a stop to it. Once the baddie's gun was dry, goblin was still on his feet approaching the good guy, other customers urged more bangs out of that Remmie, good guy held fire, got in a brief wrasslin' match with the goblin, bopped him upside the head with that 7.5" barrel at least once, goblin staggered towards the door, collapsed and later died.
Final score: good guy with Remmie unharmed, clerk mildly wounded (still up and checking on everybody else once the gunfight was over and back to work soon thereafter), nobody else harmed including a 10yr-old kid the goblin was pointing a gun at when first engaged by the good guy. Zero legal problems for the dude with the Remmie.
Oh, and the goblin was on drugs of some sort, meth suspected last I heard.
I suspect the Remmie failed due to a brass (or cheap steel?) triggerguard bending, but I'm not certain. That or the trigger return spring? We also strongly suspect he'd loaded it five-up, hammer on empty.
Lessons learned: going for cover helped a lot, controlled aimed fire ditto. Cool head most of all, including knowing his gun and knowing how to keep it running despite damage that would have turned anything else into a doorstop. I suspect he kept shot #5 in reserve in case another baddie made an appearance.
In my case, my daily carry is a NewVaq357 loaded full up 6, with VERY hot 125gr Gold Dot projectiles as loaded by Doubletap Ammo. I am very confident this load has at LEAST the same manstopping power on tap as any good 45LC load compatible with that Remmie clone or the NewVaq45, and quite possibly better.
I also know for a fact my gun is tougher than that Italian Remmie.