Pretty typical of most milsurps of the era. Sight folded down= battle sight, usually regulated for around 500 yards. It's where the old Sergeant's admonition to "shoot low, boys" came from. Where does it hit with the ladder raised and the slide in its lowest position?
As Gary said. To better understand the problem I would do some research into what ammo (bullets and powder) the Canadians were using as service rounds. That is what the sights will have been regulated for. For instance the British were big into Cordite and the Canadians may have contracted with someone local to produce the ammo. Cordite may perform much different than anything used for powders these days. This is just speculation but ammo is half of the equation in solving your problem of hitting high.
