The mob ranged item feature is great but there is one thing that would make it perfect. The ability to edit the bursts, radius and cool down time.
Bursts: How many projectiles are fired in one burst. You can also edit the time between projectiles.
Cooldown: How long the cooldown lasts until the next burst. If you want to make a mob that uses a machine gun. You could set the cooldown ticks to 5. By default it is 30.
Radius. How many blocks around the entity can projectiles be fired. Helps with bigger entities. Otherwise they just fire a tiny projectile.