I'm off to the hardware store to get some cap screws! Thanks for the writeup. Stuff like this is really useful, in fact more "tutorials" on applicable airgun projects like this one would be a really valuable additon to the forum. Guys like me that are still pretty new at metalworking can muddle through given tips like you've done with this project.
This brings me to my next question. You mentioned hardening the sleeve that the pivot bolt rides in. Could you explain how you went about it? Is it as simple as heating the metal to a certain color (straw?) and then quenching it in oil?