It is my belief that these swords originally had a 1 shaku nakago used for officer training.were then collected and fitted with standard length koshirai .
Having 2 stamps which one was stamped first,in other words is there any way of knowing chronologically it seems the larger 6mm stamp appears mostly on mumei blades and the smaller seems to appear more on Takayama blades?
To the best of my knowledge there were 3 different lengths specifications:
2.0 to 2.1 shaku
2.1 to 2.2 shaku
2.2 to 2.3 shaku
To accomodate soldiers of different heights
Nakago lengjth spec was 212 mm.
They are what they are there is no questioning that. But the facts are we really dont know all the facts. In response to ro your commentary : We all want to know more and it is a study in progress.No need to belittle what you personally do not like. But that is your decision.Let us all strive together for the good of all involved. The more we know the better off we all are.
Each of the Dojos in 1946 were 200ft long and 40 ft. Wide times 7 total equals 56000 square feet of floor space for cadet training .they must have had a large surplus of swords there at wars end that were not used in combat making them eligible for satisfying U.S. requirements for purchase as souvenir swords .
Definitely Takayama Masakiichi being a 10th Dan in Kendo,had alarge influence in Naval cadet training and later in war also for the Army training in Toyama.He Instucted Seki area swordsmith on how to build a killer blade in essense and practicality.He was one bad dude .
Tenshozan Tanrenjo produced 8747 swords in 436 days ending in March 1947 that means they produced 20.06 swords a day .Since they had 20 fitting rooms that would mean 1 sword per day per toshigi.