I removed the empty casings that were in the gun at the time. I replaced them with with six fresh rounds and proceeded to pull the trigger more than six times. I only ended up discharging the gun three times followed by three clicks. Upon reloading I discovered that all six shells were empty. I did not forget to reload those three rounds, hence saying six rounds = three shots. I am also fully aware of how the action of a revolver operates, so no shit sherlock.
This glitch occurred several times, frequently getting me killed.