Mostly this is the fault of the people who make scope mounts. They assume that the people who buy their stuff have a modicum of common sense and mechanical ability and write their directions accordingly. They are wrong on both counts. Often, people don't even read the instructions. I think it was scope-mount maker Maynard Beuhler who said, "When all else fails, read the directions." Beuhler's mounts, by the way, were handsome and very strong, and a real pain in the ass to get on a rifle properly.