FredC wrote on Apr 18^th, 2019 at 5:14pm:

. . . I thought they might have been tooling up in 1900 for the 03A3 . . . If it had been me I would have finished all that last bit of machine work (dove tail and rear sight holes) in one operation and soldered a finished base to the barrel later. They may have had a good reason for not doing it that way. . .

That would have been a very long lead time. The 03A3 wasn't developed until 1942.

The slot and pin hole for the blade would have been liable to distortion during the brazing (not soldering) and milling of the base. Leaving these operations until later ensures the blade and pin will install properly.