Here are some rough tips for any ams turret.
1: don't use explosive, missiles are never going to be close enough to each other to be hit by the radius and it just takes up space.
2:Its a bit tall for an ams and will be hard making it look even half decent.
3: have multiple outputs. A line of single barrel ams turrets is worse than just a few of 2-4 barrel ams, and they dont even have to be very large. Ive made and ams with 8 outputs about 3 times the size of yours and a line of 5 can hold up decently against a Despoiler.