All missile weapons have a maximum range that indicates the furthest distance they can shoot. If your declared target lies beyond this maximum range, your shots automatically miss. This is why you must pick targets before measuring the range.
For example, a unit of crossbowmen, whose weapons have a range of 30", declares that it is firing on the nearest Orc unit. When the distance is measured, it is found that the Orcs are 32" away. The hail of bolts therefore falls short of the Orcs.
It often happens that some models in a firing unit will be within range and other models in the unit will be out of range. If this is the case, only those that are in range can shoot and the remainder automatically miss.
These ranges are the maximum distances that the weapons can fire. Missiles lose power and accuracy long before they reach their maximum range, so ranges are divided into two types: short range and long range.
Targets within half the maximum range of the weapon are in short range.
Targets further than this (but still within maximum range!) are in long range.
For example, a short bow has a maximum range of 16". Targets within 8" are in short range. Targets that are more than 8" and within 16' are in long range. Targets more than 16" away are out of range. As we shall see later, it is more difficult for a weapon to hit a target at long range.