isn't randint range inclusive? thus random.randint(0, 6) == 1 has a 1 in 7 chance, not 1 in 6. Most revolvers, assuming this is emulating russian roulette, have 6 cylinders, not 7.
Revolvers don't have the concept of one-in-the-chamber, only semi-auto pistols do, and you can't play russian roulette with semi-autos :P (well you could, but 99% of the time, barring unexpected jams, the first person to go would lose)
Anyway I'm guessing it's a bug :) - as the saying goes "no code is too short to be bug-free"