Thanks again Bob, yes 10MB took a while to wind its way thru my encoded router, but it was worth it. She was very systematic indeed. I looked at all the pix and barely skimmed the text so far, but noticed one controversial statement:
In addition, if a gun was rammed too hard, the metal at the
breech would be strained upon firing, because it would take longer for the powder to
properly ignite and expel the shot, all the while building up pressure in the breech.
Anyway, that's a great but small collection. I'd trade most of what I own for guns no. 1 and 2, fantastic pieces.
This article has a good discussion of the function and characteristics of the crown or castle, aka cruzeta. There's an older article by Guilmartin which goes into those important items in great detail, including x-rays.