As stated above, actually shooting a rifle at different distances is the best way to get to know how your rifle shoots.
The US Marines use a 36 yd zero for iron sites and red dots. With this zero standard ball ammo stays within a 5″ circle out to about 300 yds. Bullet weight and velocity will have affect on this formula so you should test it for yourself. With a 55 grain bullet at about 3200 feet per second this formula will put you dead on at 36 yds, about 3-4″ high at 100 yds, 1-2″ high at 200 yds and about 3-4″ low at 300 yds. This is not the bulls eye accuracy one would want for competition but for self defense it will keep you center mass for a fairly long distance without having to adjust your sites. One other hint I would like to pass on is for scoped weapons after getting them on paper at 25 yds. Use sand bags or any rest you can that will allow you to let go of the rifle without it moving. After your last shot that gets you on paper, position your sites on the spot you were aiming at. Then look through the scope without touching the rifle. While looking through the scope begin to adjust the elevation and windage. You should begin to see the crosshairs moving. Adjust the crosshairs until they are aiming where your last shot hit. Take a shot. You should be very close to dead on. This saves ammo instead of shooting, adjusting a little, shooting again, adjusting some more and so on. Hope this helps