[Unclenick]

Welcome to the forum.

When I took classes at Gunsite, the 200 yard zero was what Jeff Cooper taught for all medium and high power rifles. He actually had us sight in by adjusting the sights to produce a group centered 2 inches high at 100 yards. This was regardless of specific caliber, much less the specific load. You will find this keeps the gun within the kill zone of a deer-size animal to about 230 yards without having to adjust the sights. We then learned sight picture range estimation to hold high at 300 and 400 yards and to estimate in between.

Use that 2" high POI (point of impact) as your starting point. Some flatter shooting guns will climb another fraction of an inch beyond 100 yards point and be good to 240 yards or a little more, and some slower shooting rounds will only be good to 220 yards or a little less, but within the limits of human estimation and hold error it works for all of them.

I carried the M1A through the Gunsite 270 rifle class just using unmodified standard issue iron battle sights and sighted 2" high at 100 yards with some surplus 147 grain loads I had dragged along. I used that sight setting without change when I switched to some 168 grain hand loads I brought for the longer ranges and for the shoot-off match at the end of the class. I won the shoot-off.