Thanks for comments!
About the turret: You're right, that's supposed to be some sort of field repair / field conversion - not something that comes straight out of a factory.
About the base: Sure, it is a bit small, but the tank is definitely not going to fall over: too many magnets hidden in the tracks and the base. ;) But I see your point.
I like the zimmerit idea, never seen that on a 40k vehicle before. Not sure why the turret has a differnt colo from the hull - or was this meant to show battlefield repairs? Nice scene, base looks a bit small for all tha stuff, the tank especially looks close to falling over.