During a large bore pistol shoot one day a guy a few stations over had one round make a small pop, and he just pulled the hammer back to fire another round ! The guy next to him quickly reached over and placed his hand around the cyclinder, preventing it from cycling and firing. Looking at what had happened he had handload with no powder, the not uncommon 'Ah watches teebee whiles makun lots ah ammo wit my pro gressive press', and the bullet had lodged in the barrel.
I've also heard 'bang, bang, BOOOM' during a shoot, where the guy evidently had two charges of powder for a target load. Still not as intimidating as someone's M1A going full auto on the range :^)