A bullet is affected by gravity the instant it leaves the barrel. However, the firearms are made to compensate for this because if they weren't the bullets' flight path would never cross the line of sight. Most handguns are made to shoot POI/POA at 25 yards, so between 10-15-20 meters the bullet shout actually be rising.

The head makes a lousy target for realistic shooting. Many people think that any head shot is an instant kill, or at least an instant stop. This isn't true. Unless the central nervous system is damaged the threat may still keep fighting, even if it's only enough to pull a trigger.

It does appear as though the Europeans do train somewhat like we Amercians. We assume we are going to be attacked by a two dimensional humanoid, with marked vitals or scoring rings, that will stand perfectly still long enough for us to perform a finely choreographed dance routine right in front of their faces.