Traditionally guns are symbols of aggression or anger toward others if you are using the gun or turned inward if you are being shot at. They can represent the penis; male sexual drive; ejaculation; issues of passiveness or aggressiveness, attack or defense, power or impotence, authority or dependence, masculine or feminine. Perhaps a waking situation has opened up old wounds related to any of these issues, especially if someone from your past is in the dream. Consider the symbolism of what you are shooting at.

See penis, sex, weapons.