It would make a lot more sense for the fractional chance of the gun actually firing to be based off of how many bullets you currently have loaded in your revolver. If you are on your last round, and spin the barrel, you would have a 1/6th chance of dying. If you have 5/6 rounds, you would have a 5/6th chance of dying, and so on, and so on. Pulling the trigger after reloading would be a guaranteed suicide.