I always zero at 100 yards however most whitetail i harvest are well within that distance. Last year the buck closed the gap to within 30 yards very quickly. I was shooting from a stand 25 ' in the air. I hit him high I got him but I almost missed him. I also shot a coyote from the same stand same elevation at 70 yards. I drilled him dead on. To be honest most game I take is within 100 yards. I am thinking strongly about changing my zero to fifty. But I agree that 100 yards is a good rule of thumb. I think the farthest I have target shot was 300 yards, I received a education in how much my flat rifle drops. If I remember correctly it was about 18".

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S&WCA #3012