I have both a 721 in 35 Whelen and a 722 in 300 Sav and 22-250(switch barrel). I had a Sako extractor installed in the 722 when it was giving me fits with the 22-250 brass. From what I understand you can get a riveted 700 installed(by gunsmith) find a used/new 721 extractor, have a Sako or AR extractor installed(again a gunsmith) or install a new 700 bolt (PTG/Rem and again need a gunsmith to regulate headspace). Anytime you change bolts you need to check the headspace.