Nice Rifle! Have you fired it yet?
With regards to the AA role of the sights, you have to bear in mind that the Japanese Army put great store in its infantryman, and almost the entire army consisted of infantry. They travelled light, and 'man packed' just about everything. Most of their artillery could be broken down, and they had very few tanks, and of these, they were essentially Light tanks, and primarily used only in the infantry support role. They were also were nearly always part of a large army or group. Imagine several hundred Arisaka's, firing together, at aircraft, and you now have a large amount of lead in the air. It only takes one lucky hit! The British Army still teaches to fire thirty(!) aircraft lengths ahead of a jet, before becoming to fire , en masse.....
Ps Might I ask how much you payed? :cheers: