The model is a jewel, plenty of fine details, photoetched, and many delicate parts that will ensure a crispy detailed model, outside and inside.
The different colours primers are perfect to continue with the lights and weathering without having to apply a second "base" layer. If I had used a neutral grey primer I would have to airbrush a second paint layer of the proper colour.
Pigments are essential for a dusty and weathered finish.
Again, using a proper primer is very useful to avoid appying a second layer.
http://4.bp.blogspot.com/-Q_Gy8JdbHpo/UuPvDxSCpII/AAAAAAAAMv8/5rSCzt8Jxk8/s1600/IMG_2265.JPG
base and filter for the pneumatics
Ready for shadowing and weathering
A filter with ivory colour to modulate the base colour will give the Portalnd Stone 64 tone average.

Some chipping with a sponge usinf the stencilling technique.

And some washes to shadow some details

For the Besa gun i used a silver base and further black acrylic washes to achieve the dark metal gun colour.

For the details like the gas cans, fire extinguishers, etc I used model Air colour applied with brush. For the periscopes lenses I used a silver base and later a traslucent Smoke and Blue wash.

In the end I decided to close the rear doors andlower the driver door to let the turret turn freely. Now all that is lef is to paint some stains and add a bit of stowage.

Federico Collada