Jim,
You're paint chipping technique looks good, but Bison is right, the paint underneath should be green and black. Looking at the pics I feel that there is an imbalance in the paint chipping. The top of the turret and the glacis are quite heavily chipped, but the side of the turret and shields are almost prestine. Most of the overall chipping would be caused by sandblast, and the vertical sides would have taken much more of a battering if compered with the rest of the chipping. Some of your chipping also seems to 'uniform' concentrated on the edges. I made that same 'mistake' on my Bradley
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.
I think that you should either reduce the chipping in the heavy areas, like a fairly new vehicle, or increase the chipping overall, especialy on the vertical sides, to show a very heavily weathered vehicle. The last option would visualy be quite attractive, and there are plenty of reference pics of heavily chipped British vehicles in theatre.
You made a good start, with some tweaking this will turn out excellent.
Cheers
Henk