For scopes with non adjustable parallax, most factories set these at 100 or 150 yards, likely as that is the distance most of those scopes are used at primarily.

However, if one was going to shoot regularly at 400-500 yards, what would be the downside to having parallax set at 200-250 yards so that longer range parallax errors were reduced? What degree of increased error would be seen at 100 yards set up this way?

Thank you

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