They're great, I like them! They're going to look badass on those ships.
But I think the missile turret confuses me a bit.I think it's because of the completely black texture (it seems completely black at least)
So maybe you could try to make it a bit less.. completely black? It seems a bit unreal because we can barely see the curves of the parts that are of this color and, in my opinion, it lacks details (the black texture). So using something a bit different could help maybe to see the turrets' details more clearly.
Another thing about the missile launcher, I would remove the flaps at the end of the cannons. I think they're a bit useless.