This is a technique I picked up from Fine Scale Modeler Magazine.
US armor during WWII has a rough cast texture to anything that was not flat plates such as the body and turret.
Using the thin Testors Plastic Cement(the one with little nail polish brush inside)coat the area you want to have texture.
Using the little brush on the cap start stippling where you put the layer of glue.
After a couple of passes you get a really authentic looking turrets and chassis.
This will look really good on a Leman Russ and of course any of the DUST Bots.