Longer mag boxes can be purchased at Brownells, they are made by Wyatt Oudoors. You have 2 choices for the 338 RUM, one of the boxes is .110 inches longer that factory or there is a center feed model that is .300 inches longer. The action has to be milled out at the rear of the mag port and the floor plate on BDl models must be notched. In my experience, the shorter box is long enough to accommodate most bullets for the 338 RUM, if the 300 RUM (which is slightly longer) is being used, I would reccomend the longer box. Installing the shorter box can probably be done with a dremel, however, the longer box needs to be installed using a milling machine. Hope this helps.
Todd Bettin
Bettin Custom Guns
