The Koval Millet whiskey is aged in 30-gallon new charred oak barrels (like bourbon distilleries, Koval sells all of its barrels after a single use). I was unable to find any information about the amount of time this whiskey spends in-barrel, so I would go ahead and assume it’s quite young. … Koval distillery in Chicago is an undeniable pioneer in this space, with various whiskies for sale distilled from millet, oats, spelt, wheat, and rye. All of Koval’s spirits are single-barrel releases, and all are made from organic grains farmed in the American Midwest.