Nice guess Dean but I think a more plausible explanation was that the forearm iron required replacement to accomplish the modification. Since the iron was new it required engraving and on A&B's it required more time and a higher paid engraver to complete this work. I think this may justify the 20% increase in cost over the lower grades.

Good points but the only engraving would be the screw heads on the underside of the iron and the bow of the rear of the iron, not the latch.
Come to think of it, at the wages of the day I guess $2 - $3 or so was a very fair price for the extra work.





.