Abstract: An essentially jam-free bulk loader for a semi-automatic paintball gun includes a storage housing positionable above the gun infeed opening and adapted to hold a quantity of paintballs to be gravity fed to and fired by the gun. Extending downwardly from a bottom outlet opening in the housing is a feed tube having a bottom end portion connectable to outer end of the gun infeed elbow. During normal operation of the loader, a series of paintballs fall into the tube and infeed elbow and are vertically stacked therein for sequential downward delivery to the gu through the inner end of the infeed elbow. If a paintball jam occurs within the storage housing above its outlet opening during firing of the gun, a void is created in a top end portion of the feed tube above the downwardly moving paintball stack. An optical sensor detects the void and responsively actuates a motor driven agitator member within the storage housing adjacent its bottom outlet opening.