once I get all the kinks worked out, yes, I'll probably post a how-to-to-it kind of thing.
GP11 is what I am mostly working on too.
basically, I am depriming them the annoying and slow way with a pick/lever, then drilling the anvil, then using a hydraulic press to swage a large ball bearing into the pocket to decrease the size. Then use a large rifle primer pocket uniformer (end mill cutter with smooth sides) to shape the bottom of the pocket. Some variation on order of operation, methods etc.
so far, the standard large rifle primers are pressing in nice and tight, but not overly tight. they are air tight as well. They also sit a tad higher than with Berdan primers. I also sized and deprimed in the normal way on the press and had no problems at all.
as well, if you swage that pocket deeply, without damaging the case head, and you cut it with the pocket uniformer, you end up with a decent bearing surface, not just a knife edge.
I think I am going to drill before I swage however. I ruined a few cases with the drill bit. if its not swaged, the sides of the pocket are still flat, so less chance of frigging it up and not being able to fix it. I think at least one of them could have been fixed if it was swaged afterwards.
this would be an easy operation if I had a machine shop, but I am just using things I have access to.