One more comment
Since I'm not a gunsmith, there are a lot of folks more qualified to expound on this subject...just my experience.
RE: 700 actions for Lapua .220 russian brass.
The web on Lapua .220 Russian cases is not very thick - I'm sure someone here has a spec, I just have my samples...
A remington bolt face is may be counterbored to around 0.150". If the gunsmith faces the bolt, it may actually end up a couple thousands deeper.
There is a small and probably necessary gap between the bolt face and the end of the barrel tenon, and the inside edges of the chamber are generally chamfered for easier chambering. If the gap between the bolt and the tenon, plus the chamfer, plus the counterbore is greater than the web thickness of the lapua brass, (not hard to do), then the ignition pressure will be contained (or not) by the thin walls of the unsupported portion of the case just ahead of the web.
In this situation, you may find that your brass gets a ridge, much like a miniture belted mag, just in front of the web of your cases where the thin walls of the brass are unsupported. If you're shooting intense loads, and you've done things like having the firing pin bushed where you're not picking up on normal pressure signs, the brass will rupture along this ridge and blow out (In my situation, through the slot milled for the sako extractor). The ejecta will bloody your nose, forehead and cheek - safety glasses are advised for this activity.
There are a lot of remingtons out there rechambered to PPC that work just fine. There are a lot of great gunsmiths out there who do rebarreling work that is absolutely great. And you may never push a 6 PPC to pressure limits where this will be a problem...
As for me, I'd seek some more advice from some of the gunsmith on this forum who understand the mechanical differences between re-barreling for a 30-06 and .220 Russian.
JM$0.02...