Almost all of the military rifles of the period, early 19th century, will shoot about a foot high at 100 yards with the sight at the lowest setting. I don't understand why they did this but the designers were building rifles that were supposed to be making aimed shots at 500 yards or more. None of the graduated markings on the sight will be of really much use to you. (1200-1800 yards?)
I have a Yugo M48, that made nice tight groups at 100 yards, about 10 inches high from my point of aim. I thought for a while about trying to fit a taller front sight to get things on the spot. Seemed complex. I looked at the rear sight and realized that at the lowest setting the sliding leaf sat on the base of the rear sight, there was a small amount of room there for adjustment. I flipped the sight forward and carefully used a file to take some material off of the underside of the slider. This allowed the sight to settle lower into the sight base. I used a dial caliper to measure its position before and after making a small adjustment. After a few passes I felt like I had lowered the sight enough. Something like 0.06 inch removed.
I took it to the range the next day and it drilled a five shot group about 1 inch above point of aim, that made me smile. I shot a second goup to confirm and I was a happy camper. None of the finish of the gun was affected, it is a very clean Mauser, as the only adjustment was the underside of the slider.
I don't really see myself shooting this rifle at anything greater than 100 or 200 yards. Now it'll drill them in there for me. The slide is still there if'n I feel a need for a 1500 prove my manhood shot.