Just pick up an M16/AR15 extractor assembly and you're good to go with the exception of a longer pin due to the larger diameter of the 700 bolt body vs. M16/AR15 bolt body.
M16 Style Extractor
This simple but effective design works just like the extractor in an M16 rifle. Will not pull out like other extractors if a sticky cartridge is encountered. Used by the Naval Surface Warfare Center in Mk 13 sniper rifles. Made from Pre-hardened 4142 steel. Gunsmith installation required.
P/N 306-91 Magnum calibers
P/N 306-92 Lapua/Rigby based calibers