The U.S. Metric Study was completed in 1971 and their published report recommended we should “go metric” on a carefully coordinated national program. Congress passed the Metric Conversion Act of 1975 and established a U.S. Metric Board, but a timeline was never established for metric conversion. U.S. arms producers like the General Electric Armament Systems Department, followed a government directive mandating that new guns should be metric. They complied in the next product they released, making the drawings for the newest Gatling gun totally metric. And what about the ammunition feed system that connected to it? It was produced using inch system dimensions. Why? Because the government directive said the guns had to be metric, but made no mention of the feed system, so it was a half measure at best. This was typical of the resistive mood of the country towards the metric system. After years of public apathy, spending money, and achieving only marginal results, the U.S. Metric Board was disbanded by President Reagan in 1982.http://www.sadefensejournal.com/wp/?p=710
Определенно,по 5 бальной шкале - это твердые "5 баллов", без вариантов.
Ну и много интересного по ссылке о метрической системе, которую так до конца и не приняли в качестве единой при проектировании образцов стрелкового вооружения.