Hi Dean,

I've seen it many times before on models and always wondered why the primer or undercoat is sanded almost completly off... It would seem that you're doing it to save weight. It would also seem that you are using the primer as a filler. I always thought that the purpose of primer was to provide a uniform base for the final colour to adhere to. If the primer is sanded off, how well does the paint stick and cover? Perhaps if the primer was not sanded off a lighter coat of colour could be used...

I'm sure there must be very good reasons etc.

Cheers
Jason.