The .300 WHizzem is not known for smooth feeding to begin with.
The few factory rifles now chambered in it finally got it right, but some of the early Model 70's chambered for it didn't.
Your mag box is maybe already blocked for the .308 length now, so that wouldn't be necessary.
Open the bolt face & extractor & mag follower to belted-mag specs. (Yes, I know it isn't a belted mag, but it is the same size case head.)
All the Wheeler rail milling fixture is, is a clamp to hook the receiver recoil lug and hold it down on a milling machine table.
It has nothing to do with the actual shaping of the feed rails.
It is just a clamp.
Modding Mauser 98 feed rails is more an art then a science.
I just don't know how it would work out with the short fat WHizzem case.
But I do know you only get one chance to get it right once you start grinding or milling metal off.
rc
