In October 2004, it was announced that all generally-available Jack Daniel's products would thenceforth be bottled at 80 U.S. proof (40% alcohol by volume), which is the highest proof allowed in some U.S. jurisdictions; this also simplified the production process.
Previously, the famous black-label brand (the better-quality, higher-priced product) had been 86 proof, where legal, while the lower-end green label was 80 proof; these marked reductions from the previous practice of bottling the black-label product at 90 proof and the green-label product at 86. Both are made from the same ingredients; the difference is determined by professional tasters, who determine which of the batches will be graded as worthy of being labeled with the prestigious black label, the rest being sold under the green label.
One more thing, Jack Danielís doesnít rotate barrels. (Makerís Mark do it)