Vis is spot on. The methodology of the series-marking was devised as a way to contain the serial number marking as short as they could to prevent a looong digited serial number as the weapons are mass produced, and was strandarized for all weapons.
The bayonets which were produced in much more numbers see the higher "Two Hiragana" series territory that is elsewhere only seen on the Mukden T-38 rifles (but just due to allocation of serial number blocks, not the actual number produced at Mukden). The following is a cut-and-paste of a correspondence I made just recently for one of our important members here. It's pretty convoluted, but if you read through, you get the picture.
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In follow up to our conversation today, I checked the markings regulation of 1943 and confirm that the character codes (series) to be used from range 100,000 to 4,899,999 shall be a "single en-circled Katakana" in the I-Ro-Ha order, and from range 4,900,000 and upwards shall be in "two Hiragana" character codes starting from I-I. A quick translation on that instruction will go as follows ;
- Serial numbers shall normally be within a 5-digit range. Hence if the number reaches the 6th digit, it shall be kept within 5 digits and specific codes shall be added to the top, per following method (BTW, this description proves that a specific "series" will start with a 00000, and end at 99999. TJ) :
1) The size of the code shall be the same as of the serial number, and positioned on the left of the numerals of the serial number in the same interval spacing as between the numerals.
2) Serial numbers 100,000 up to 4,899,999 shall be coded with a Katakana which is to be encircled and placed in order of I, Ro, Ha .....
Some examples of such markings : Actual number / Marked number
1 / 1
99999 / 99999
100000 / Circled Katakana "I (イ)"- 0
199999 / Circled Katakana "I (イ)"- 99999
2000000 / Circled Katakana "Ne (ネ)" - 0
3456789 / Circled Katakana "E (エ)" - 56789
4899999 / Circled Katakana "N (ン)" - 99999
3) Serial numbers 4,900,000 and above shall be coded with two Hiragana characters preceding the 5 digit numerals. The first Hiragana to be defined as "1st Code mark" and the second Hiragana to be defined as "2nd Code mark". When the serial number reaches 100,000 increments, the 2nd Code mark shall change in order of I-Ro-Ha, and when the serial number reaches 4,800,000 increments, the 1st Code mark shall change in order of I-Ro-Ha.
Some examples of such markings : Actual number / Marked number 4900000 / Hiragana "I-I" - 0
4999999 / Hiragana "I-I (いい)" - 99999
5000000 / Hiragana "I-Ro (いろ)" - 0
5099999 / Hiragana "I-Ro (いろ)" - 99999
6900000 / Hiragana "I-Na (いな)" - 0
8356789 / Hiragana "I-Te (いて)" - 56789
9699999 / Hiragana "I-N (いん)" - 99999
9700000 / Hiragana "Ro-I (ろい)" - 0
9799999 / Hiragana "Ro-I (ろい)" - 99999
9800000 / Hiragana "Ro-Ro (ろろ)" - 0
9899999 / Hiragana "Ro-Ro (ろろ)" - 99999
11700000 / Hiragana "Ro-Na (ろな)" - 0
13156789 / Hiragana "Ro-Te (ろて)" - 56789
14499999 / Hiragana "Ro-N (ろん)" - 99999
230500000 / Hiragana "N-I (んい)" - 0
230599999 / Hiragana "N-I (んい)" - 99999
230600000 / Hiragana "N-Ro (んろ)" - 0
230699999 / Hiragana "N-Ro (んろ)" - 99999
232500000 / Hiragana "N-Na (んな)" - 0
233956789 / Hiragana "N-Te (んて)" - 56789
235299999 / Hiragana "N-N (んん)" - 99999
Somewhat complicated explanation, but hope this helps !
Warm regards
Takehito
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So, serial #235,299,999 would have been the end of the line for a T-30 bayonet have the war lasted longer !