MagnumHunter:
Apologies, just realised I had forgotten to respond to your request.

Centre of front guard screw to forend tip is exactly 18cm, just over 7 inches. Hope this helps with your project.

93x64mm: have had AR2209 loads sitting there for over a week now (my time is not my own at the moment) but intend taking them to the range tomorrow. Will add results to this thread when they are to hand.