An update to this topic -
I have received confirmation that the "W9MM" headstamp brass is manufactured by Armscor in the Philippines. Armscor started a new production facility up in Stevensville/Victor, Montana called Armscor Cartridge Inc. which produces and sells ammunition under the Armscor name. American Quality Ammunition is also out of Victor, MT and they utilize this brass for the ammunition they produce and sell. However, Armscor/ACI also sells this brass as an OEM component brass but only to other manufacturers.