Some weapons sacrifice a speedy reload for hitting power, making them impossible to fire on the move.
Move or Fire
A weapon with the Move or Fire special rule cannot be fired in thephase if the model moved earlier in the turn, including rallying, reforming and pivoting on the spot (except for Lone Models, who can pivot and fire in the same turn). This even applies if the model in question was forced to move as the result of a spell or other such compulsory action. Mounted models with Move or Fire weapons may still move and fire, but they may not March if they do so, unless specified.