When a new reloader asks this question I often say; clean them just like you'd clean your gun. Use bore solvent, brushes, and lightly oil. I keep a "soak" of mineral spirits, Kroil and ATF in my bench and occasionally just drop the whole turret, with dies, in the soak and let it sit (I sometims forget it's in there so the soak can last for a few hours to a couple days). Then I'll slosh around use a paint brush or nylon brush to get any lube out and drain. A quick wipe finishes the job. There is enough oil left on the dies to prevent rusting....