It depends on what kind of roulette you are. The most classic one is to place only one bullet in the 6 bullet holes and then spin the wheel.

Assuming that the process of turning the wheel is completely random, that is, you cannot control which space is dialed, then there is a 1/6 probability that your first shot will hit the space with loaded bullets. , that is, the probability of you killing yourself is 1/6. If you are not dead, then give it to the opponent. The probability of the above event happening is 1/6, so the probability of not happening is 5/6. That is, the probability of you not dying in the first shot is 5/6, so the opponent will die in the second shot. The probability is 5/6*1/5=1/6, which is also 1/6. So no matter which shot, the probability is 1/6, until one party dies.