how to lengthen magazine box?

[rufous]

Is it possible to lengthen the magazine box area of a Winchester Model 70 Classic Stainless? I have one in 300 Win Mag that has already been converted to the 300 Weatherby length (3.600") by installing the longer box and shortening the bolt stop and ejector blade but it is shorter than ideal. My rifle has a longer throat than I wanted and the 200 Nosler Partition is touching the lands at 3.595". If I could get the box about 0.030" longer then I would have some breathing room in there to ensure smooth feeding. Rufous.