Actually 8 directions is better for an enemy bullet. Once the bullet is created(IF 360) it will have to turn towards the player sprite before it can start moving towards it. with 8 directions the sprite can instantly flip around and start moving. You were talking about the bullet having bad accuracy? just change the Inertia to zero. This will create 100% accuracy(which is not always wanted though) 360 bullets are alot slower when it comes to turning. 
Actually 8 directions had too much accuracy, the bullet would follow you around.
