Would any of you guys be kind enough to direct me to the best/cheapest place to buy a mag box for a 300 wsm? I'm turning an ADL into a BDL McMillan and thats the one part I'm missing.

They seem to be unobtainium from my normal online sources....

Midwest Gun Works? Numrich Arms? Direct from Winchester?

Hmm, how about this ?

http://www.midwestgunworks.com/page/mgwi/prod/winchester-model-70-magazine-box/U353071340

Or maybe this ?

http://www.gunpartscorp.com/Products/1316740.htm

Wow, thanks WiFowler. For some reason when I checked numrich, midway, brownells, etc, they all only listed an "extended magazine" which was longer that standard. Should have looked harder, thanks.