Hey Check this out I did some research and this is what I found

www.wiki.answers.com: If catapulted with the same force, will throw objects the same distance.
www.chacha.com: A heavier mass will result in a shorter distance of a catapulted object.
www.siriiusscience.plowworks.com: The weight of the object will be taken down by gravity like heavy can slow down its distance.