In your book , in the section on the 1866 rifles you say "The hammer nose was slightly angled, as is the rear of the breechblock comb, so that the joint between them did not form a line perpendicular to the bore, as would be expected, see Figure 3-11, arrow. The reason for this unusual feature, observable only from the top, is not known."
It's not known because there is no documentation as to why? I'm sure this was covered in the past but was curious as to why it was put that way. thanks for writing the book too! JW