Modern tanks have a rough texture ont eh turret and hull tops. this is to prevent the crew from slipping and sliding when wet. In actuality this is most times an epoxy coating sprayed on the top of the vehicle. Most model companies tend to leave this texture off their models. A simple way to replicat this is to get some Mr Surfacer 500 in the bottle. Stipple it on with a small square brush and keep stippling until it starts to get rough. Let it dry and then paint over with the appropriate colors. Tamiya liquid surface primer in a bottle can work to the same effect but takes more stippling to get it to look effective.
Here is an example of the texture from my current STRV build.
Here is an example of the texture from my current STRV build.
