Custom arrows? (HELP PLEASE)

hmm, this one is not completly obvious, in base java minecraft the only things that can fire from a bow are arrows and potion arrows, however you can replicate this via global procedures, when a player uses right clicks with an item you can check if that item in mainhand is bow or crossbow. you can trigger the animation by swapping said item in your offhand or the target item for an arrow. this counts as using an item. when doing this use another global procedure that detects when a player is using an item (and make an if statement for if its a bow or crossbow) and your desired projectile item is offhand, when letting go of a bow or firing it, it counts as finish using an item, another global procedure to check wether or not your projectile item is in your offhand and your holding a bow, you can despawn the arrow as it counts as a immdient source entity, then shoot your projectile with whatever code you want. crossbow, when finished charging it counts as finishing using the item, you can swap the crossbow for a custom one that shows your projectile in it, then simpily when used it will give back your crossbow with minused durability