Ranged Item Without Projectile required

You would probably just make a procedure which, when the item is swung, uses a projectile function to fire a custom projectile of your choice. (Just set the velocities to the x/y/z look angle vectors of the player, multiplied by a whole number or a decimal depending on how much velocity you want the projectile to have.)

The solution by Mindthemoods is the intended one. Built-in ranged system is a convenience system so one does not need to use procedures for regular "required item" shooting where an inventory scan is needed.

For shooting in any case, use right click trigger of item to launch projectile using procedure blocks in the projectiles procedure blocks section