You can use any trajectory caclulator on the web and see that rounds like the .223 and others will be dead on around 175 to 225 yards if you zero at 50 yards instead of 100 yards. The bullet rise at 100 yards will only be about 2 inches or so, which means you can aim about dead on from 50 to 200 yards and hit a small target area. It's just easy to zero in at 50 yards compared to 200 yards, especially with iron sights. There are even indoor rifle ranges with 50 yard targets.
But you have to get a very small grouping zero at 50 yards because that grouping will expand a lot at 200 yards ( angular displacement). A two inch group at 50 yds is an 8 inch group at 200!