My groups at 100 yards were about 4 to 6 inches, but with my eyes having more than 6 decades of usage, I really cannot shoot very well anymore with open iron sights. I could do much better with a scope. I suspect this rifle is capable of better groups than I got.

According to the photo, my sight is the 96 model.  My model 1898 rifle is a relatively early one (#156001), and someone (maybe you) said it was common to put the 96 rear sight on the early 98 rifles.

Another thing about the rear sight-- When I move the slider forward, I don't see the sight being lifted until I move it forward of the 1000 yard mark.  That makes me wonder if the sight is not installed right or if it might have heavy wear or might be missing a piece.