Glad you all like the weathering - I wish i could say it was a secret process but it's just a very quick process. Prime, Sponge on your rust colour (a brown/red mix ) add a matt varnish, add a layer of chipping medium, then paint your surface colour and detail - let that dry, soak it with a damp brush and then go to town chipping it with a screwdriver.
Give the whole thing a brown wash, add some rust and streaks with a bit of GW contrast paint and then finally some pigment for dust.
All done !