Agriculture's authorization and fixed-total-use quota regime ended December 1, 1946. Distillers then operated without total-use production quotas until a 60-day voluntary grain-conservation shutdown began in late October 1947.
The December 1, 1946 transition is verified in WFO 141 Amendment 4 and WFO 141-1 Amendment 3. Two complete Truman presidential records independently verify the 60-day voluntary shutdown and its December 24 endpoint, while differing by one day on the October start.
This was not absolute deregulation: commodity-specific wheat, corn, and rye restrictions and reporting rules remained after December 1. Use 'late October 1947' for the interval's endpoint unless explicitly discussing the one-day discrepancy.
Contemporaneous Agriculture rules establish the start; two primary presidential records establish the later voluntary shutdown.
Publication-safe when described as freedom from fixed total-use quotas, not freedom from every federal grain rule.