I missred what SubThermal wrote, i thaught it said "Because the green version weights more than the black, everyone knows that".
I have e-mailed Sako´s office in Sweden, but have not recived an answer yet.
Sorry to bring up a 3 year old thread, but I thought I'd give it a resolution for anyone who wants know in the future. I contacted Beretta to ask the same question and got this reply after 3 weeks: "The phosphatized model will have a heavier green stock. and a side rail attached to the F/E."
Not sure why green is heavier, but I guess an added rail would make sense. Hope this helps someone.
The Green stocks , are the Military version of the std stock , and the main point is the stock is 1/2 pound heavier as Its a stronger version , it is also Green in colour & has different sling attachment points .