Damn, I just wrote up a big post, but it timed out... Anyway, the short version was thanking everyone for their help so far. The action showed up this week, so I'll have some time to mill off the ears and get it sorted out.

I've gone back to the .510 Wells idea (using the .460 case), because aside from the issues Altamaha listed, I feel it will probably be easier to get a belted case to feed a little better than the rimmed case. In theory anyways.

But again, thanks for all the help, and I will post a few before/after pics of the action here soon. Cheers!