I always wonder when I read of these scope tests, is the first shot movement the scope's fault, and could any fixed procedure used before and during testing help to determine this?
After a long career in mechanical engineering and lots of testing of products and designs, I have observed that test equipment, and equipment under test (EUT), may need a couple cycles to "settle in". Erroneous data on the first cycle is not uncommon because of fixture or EUT initial movement. This was particularly true in testing load cells which measure movements much smaller than these scope movements.
For scopes, which in general, have a screw to push the internal tube, and a spring to move it the opposite direction, are likely to have some hysteresis. In addition, like any screw advanced device, always moving it in a direction where the screw advances the adjustment is a requirement for accurate data. For example, machinists will always approach a cut from the same direction, backing off a couple turns, then advancing inward to the setpoint.
I could imagine that a scope, after installation on the fixture, having the turrets cycled from full up and full right ( maximum spring assisted movement) to full down and full left, then back to full up and right, then to the zero point. After which, all adjustments are made in the positive "screw in" direction, and if required to go "screw out", it be screwed out 1 full turn, then screwed in to the setpoint each time.
As far as movement on the first shot, I myself cannot fully assume it is the scope adjustments that are moving. It could be a "settling in" of the fixture and the mounts. Perhaps a couple shots should be made before data recording starts. Movement after this point is definitely erroneous.
For those who say "when I step up to the line, the scope had better hold whatever adjustments I input, including the first shot", I agree with you. Once mounted, and fired a few times, you must depend on the scopes repeatability.
Please do not take this post as a complaint about the testing, it is just my mental rambling on the concept of "move on the first shot and it fails". Also please note that JET did NOT say, "move on the first shot and it fails", I postulated that concept. JET simply posted the data, and explained his actions in post #6. He did state the one scope that moved multiple times was going back to the manufacturer.
I am NOT disparaging the testing done by JET, and I recognize his EXTENSIVE experience in correlating his test data to his competitive shooting experience. He knows when a scope is not to be trusted. We should all thank him for his efforts, and for publishing his data.
