I call this Part 3, because there are at least 2 prior evolutions of Precision. First, there was the addition of Swiss movements to Precision grade; second, the addition of Precision-grade Verithins.
For Part 3, there are two important premises I will ask us to weigh and either refute or accept.
Here is the first premise: Gruen began marking movements for new requirements in mid-1909 (in Switzerland).
• The 1909 Payne-Aldrich Tariff came into force at US ports on August 6th 1909 (see Tariff itself, as well as FOSC Vol 27, No 238, p1621). However, the proposed tariff text was published already on April 6 (FOSC Vol 27, No 86, p608) and its marking requirements spelled out on April 15th (FOSC Vol 27, No 92, p653). It was a foregone conclusion the bill would pass in similar form and go into effect the day after passing.