A rye whiskey grain bill is a recipe for the mash used to produce rye whiskey. It specifies the proportions of different grains that are used in the mash, which can include rye, corn, barley, and wheat.
The grain bill is important because it affects the flavor and character of the resulting whiskey. Rye whiskey is typically made with a high proportion of rye grain, which gives it a spicy, peppery flavor. The other grains in the mash can be used to balance the flavor of the rye and add complexity to the whiskey.