It might be a bit of a localisation but Its fine. If it was an actual person in the story saying that line, I would agree with you but I feel like the narrator is speaking from the perspective of the current era so using those kinds of phrases is fine
even with the advantages and technology inputs, assuming it is a rifled gun of some kind, would the japan of that time even have the capability of making rifled barrels?
wtf is going on? did i miss a chapter or something? we were in the middle of a siege then we're randomly in the capital talking to the priest then we're in tokugawa territory helping survey the area. why am i the only one who seems to have a problem with this?