Joe, I am not sure, I have thought it was just a cost reduction. They might have seen a drop in demand for tang sights, the 29S that came equip with the No 30 tang sight was dropped in catalog No 76 with a price list dated Jan 2, 1942. The No 30 Tang sight was listed in the 1942 parts catalog but was not in the next catalog from 1946 (first I know of after 1942 due to the war). Along with that they dropped checkering on the 29B's and also had a cheaper looking finish to the trigger guard part of the receiver.
I have not seen a lot of the 29's with the No 30 tang sight even though it was offered as an option from the factory, actually I've not seen a lot of these with any brand of tang sight.
