Can you cheat at Russian Roulette?

Surprisingly, yes.

Pусская Pулетка, (russkaya ruletka )is a lethal game of chance in which a player places a single round in a revolver, spins the cylinder, places the muzzle against his or her head, and pulls the trigger. "Russian" refers to the supposed country of origin, and roulette to the element of risk-taking and the spinning of the revolver's cylinder, which is reminiscent of a spinning roulette wheel.

Because only one chamber is loaded, the player has a one in x chance of being shot; x is the number of chambers in the cylinder. So, for instance, if a revolver holds six chambers, the chance is one in six. That assumes that each chamber is equally likely to come to rest in the "correct" position.

However, due to gravity, in a properly maintained weapon with a single round inside the cylinder, the full chamber, which weighs more than the empty chambers, will usually end up near the bottom of the cylinder when its axis is not vertical, altering the odds in favor of the player. This only applies to swing-out cylinder type revolvers, and only if the cylinder is spun outside of the revolver and allowed to come to a complete stop before being locked back in. The number of pulls of the trigger before a round is expected to discharge is 3.5 (without spinning between the pulls) or 6 (with spinning between the pulls).
In this famous film sequence, (click the last sentence) was De Nero aware of that advantage?  It looks like 'maybe.'