As someone who has both owned and shot a revolver, this is almost 100% wrong. The cylinder will only pop out on one side (the left) and in no way does this affect the firing pin when struck by the hammer from the gun. Also, once locked into the frame it is impossible to get the cylinder to rotate two directions as the gears will not work at all if damaged and you cannot modify it to do that. This would have made more sense if the author had the girl palming the bullet when spinning the cylinder.
Ok, rant over. Lil' Sis has some massive boobs so followed.