Thanks, guys. I was attempting to get a well-used look.
Sean, it is "whitish", although not quite as bad as the pics would indicate. I was trying for a very chalky look, and used an acrylic burnt umber tinted wash, heavily thinned with rubbing alcohol. The mantlet and barrel are clean, since the crew would be keeping those areas cleaner from contact when they're mounting/dismounting the vehicle (my theory anyway). I'm not sure if I like it, and may go back and dirty those areas up a bit, but not much.
Thanks for the feedback, much appreciated.