[Konstantinos]

There's something called "Lag Shooting". The SA-MP's sync is not that good and the players are not where you see them in your screen. If a car is moving, you need to aim and shoot in front (always to the direction it's moving) of it.

The same goes for DMing. You need to shoot in front of the players in order to hit them. Use ******/******* and check it out.