User blog comment:Tankburger1235/Weapons?/@comment-4890664-20120523090720

In the Book Titan's Curse Annabeth's dad uses celestial bronze bullets fired from the Sopwith camel machine gun

in The book the Lightning Thief Ares sword appears as a rifle before he battles Percy

In the Lost Hero Annabeth suggests a shotgun for Piper but puts it back saying it is too flashy so demigod guns can and have been made/modified