Somehow, my post last night didn't post, so I'll try again.

Louis, thank you. I think that will work perfectly, and there are a couple of places I can check here this weekend. Worst case, I need a trip to Vienna! Strassburg would work, too.

I took some photos, but forgot how to post them at my ISP, so I will work on that. Long story short, I got the bolt apart, and it really needed it. Not sure what was previously used to lube it or act as a rust preventative, but whatever it was, it had turned almost solid. Cleaning it will be a several day task, and I'll let soaking in cleaners do most of the work.

There is a set screw on the firing pin nut that registers the diopter. That must come out first. Once that was out, all was easy.

I'll get some photos up soon. Thanks again to all.