In Cecil’s column, “How does the earth’s rotation affect the path of a bullet?” he discussed the Coriolis effect. This led to some light discussion and a thread discussing the calculations. There was also a thread General Questions recently.
Having read all of the above, I believe snipers take the Coriolis effect into account when shooting long distances. I also believe that we’ve never heard a sniper confirm this explicitly. A recent episode of Mythbusters was trying to determine whether a human could dodge a bullet fired directly at them. During the aftershow Jamie said that they took the Coriolis effect into account. Apparently they also had to account for the rotation of the bullet imparted by the rifling of the barrel. That certainly came as a surprise. The sniper was up to 1200 yards from his target.
So, Una Persson, it looks like your math holds up in real life. Pretty cool, no?