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 **** under the green label.
One more thing, Jack Danielís doesnít rotate barrels. (Makerís Mark do it)