emcon5, thanks for the link to that old training film. I watched it when in the USN Fire Control School in San Diego, CA, back in 1956. And to see those fire controlmen around those computers operating it brought many memories of what I did in main battery plot on two old WWII destroyers from early 1957 to early 1960. I also operated the stable element that put ship roll and pitch values into the computer to correct gun orders as well as close their firing keys (Navy jargon for 'pull the trigger') that fired the 5" gun battery.
4runnerman, what I mean is the sight's elevation axis moves parallel to the barrel's elevation axis to compensate for bullet drop. From zero to some distant yardage, the bore has to elevate up to some angle to compensate for bullet drop. It's important that the sight's elevation axis is parallel to it. If the sight is 1/3 inch to the side from the bore's vertical up-down axix but parallel to it, there'll be no more than 1/3 inch parallax difference between them at any range.
If the sight was 1/3 inch to the left of the bore but zeroed to print groups 1/3 inch to the right of the aiming point, when a 1000 yard zero was put on the sight, that long range group would center 1/3 inch to the right of the aiming point.
If you have a 1000-yard long 1x8 standing on edge, it's right side (bore axis) would be 1 inch away from its left side all along its length. One side's the trajectory's vertical plane and the other side (sight axis) is the sight's vertical plane. They're both 1 inch apart at each end.
4runnerman, what I mean is the sight's elevation axis moves parallel to the barrel's elevation axis to compensate for bullet drop. From zero to some distant yardage, the bore has to elevate up to some angle to compensate for bullet drop. It's important that the sight's elevation axis is parallel to it. If the sight is 1/3 inch to the side from the bore's vertical up-down axix but parallel to it, there'll be no more than 1/3 inch parallax difference between them at any range.
If the sight was 1/3 inch to the left of the bore but zeroed to print groups 1/3 inch to the right of the aiming point, when a 1000 yard zero was put on the sight, that long range group would center 1/3 inch to the right of the aiming point.
If you have a 1000-yard long 1x8 standing on edge, it's right side (bore axis) would be 1 inch away from its left side all along its length. One side's the trajectory's vertical plane and the other side (sight axis) is the sight's vertical plane. They're both 1 inch apart at each end.
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