Yes there are just a few pages on U.S. hammer guns. Does cover ammunition but not re-loading. Certainly quite a bit on repair, renovation and gunsmithing.
Not yet fully gone through it but it should cater for most on this site interested in hammer guns. I've found a couple of typographical errors and a couple of picture title errors but they are of minor concern only. I don't think you will be disappointed and the illustrations are clear and extensive.
The title for the chapter; four pages, on U.S. guns is 'American Exceptionalism: the unheralded heroes of U.S. Gun-making'. Lagopus.....