I had that happen on my 700 as well, same screw even. I am a machinist and have my own machines and tooling, so while it was kind of a pain in the ass with all that it was possible. Almost every time I tried to take a short cut, something went wrong. So if you don't have access to a milling machine and know how to use it, I wouldn't try getting that out. You will likely do far more harm than good.
In case you do have a mill and the knowledge, here's what I did:
I used a drill bit smaller than the minor diameter of the screw holes-sorry its been a couple of years and I'm not exactly sure what size it was, just that it was smaller. I didn't have a left handed drill bit, but that would've made the job much easier.
CAREFULLY drill the shaft of the screw being very careful of your depth, because you'll be drilling into your barrel tennon if you go too deep. This is why I used a milling machine. You only have a few .001" to work with. Alternatively you could pull the barrel, which would leave you with a through hole rather than a blind hole.
If the pieces don't come right out, use a small pick or something to CAREFULLY get them out.
I ended up needing to clean up the threads with a tap because I wasn't as careful as I should've been.
If you don't have a mill, I probably wouldn't try this on your own. If you do, you'll probably still end up taking it to someone. It will just cost you more.