Here is a little demonstration on how I did the worn paint weathering on the Bradley.
Items required, a fine mist spray bottle filled with water (I use distilled), some salt, either table or cooking and the item for weathering.
If the water beads together, add a tiny amount of soap to break the surface tension if needed.
Sprinkle some salt over the areas for weathering. If the grains are too big, then crush the salt up a bit. It all depends on what effect you require in the end.
Leave the parts/model to dry overnight, or if you need to dry it quickly, use a hair drier on a warm setting to speed it up.
Give the model/parts a coat of the final colour ensure an even coverage.
Leave the model/parts to dry thoroughly at lease overnight to prevent you removing soft paint when rubbing the salt away. This was a quick demo I have done here, but when doing it properly, I would have spent more time sprinkling the salt around the model or pieces.
I hope this have been some help to you all.