riceone-
If Taylor's article is correct, the ammo was reduced in some dimensions at the time the machine gun was introduced. However, the Japanese continued to chamber the rifles to the original specifications. The rifles functioned just fine with the new undersized ammunition and the slight case bulging was insignificant militarily.
It will be really interesting to find whether your Type I has the same "oversize" chamber. I've read (can't remember where) that the Japanese sent quality control inspectors to the Italian factories, and that the Type I's were held to pretty tight standards. Both nations were (and are!) capable of building arms of extremely high quality.
Thanks for your input.
--Bob
