What are everyone's thoughts on opening the boltface of a Remington 700 from the 308 case head to the 300 wsm case head? I know there are several gunsmiths that refuse to open a 700 up to take the 378 or Rigby case.

It is a simple case of opening it up and installing a SAKO type extractor. There are a lot of thoughts on this on earlier threads. I like to solder in a 4140 bushing to fill the old extractor goove. It needs to be a little bigger in the web area than a belted mag since the WSM is a little fatter.

I built my WSM on a 700 short action by removing the riveted extractor and machining the bolt out to mag. specs. and re-installing a rivetted magnum extractor. It works perfect. The procedure was explained to me by Bill Leeper, a regular poster.
I've soft-soldered 4140 bushings in the snouts of a number of bolts after boring them to about .620 or whatever is needed to clean up the undercuts. I've also done it to salvage bolts that have been abused and had the snout damaged such that they will no longer hold an extractor. These bolts received Sako type extractors.

I've heard that Sierra uses a Savage for a switch barrel action to test the 338 Lapua, someone said it says this in the new manual so they emailed them about it. Said they have a few Savages they use to do testing with, easier to just screw on barrels and plenty strong.

My 30/338 Lapua IMP and my brothers 338/378 WBY are both on 700's, which use Sako extractors.

Here's a pic of the bolt face on mine.

George Gardener at G.A. Precision will do them too. 300 WSM isn't a big deal either.