Very interesting.

Since your gun was shipped almost 2 years later, it could very well have been an extra one of those earlier frames (also called an 'over-run' frame) with the 'military target' sight, i.e., Bisley Match sight, but assembled as a 44.

Roy's letter does indicate the sights are factory in his letter above. And even states it was manufactured in a group of 455 guns, but he didn't say it shipped with them. I think his assumption that yours was a 455 was based on that, but an incorrect assumption since yours is an original 44, or factory converted to 44 2 years later when an order came in for a Bisley sighted 44 Spl.

How about some close up photos of the rear sight; top and side view?

__________________
Jim
S&WCA #819