Bardstown Bourbon Discovery Series #4 – The fourth release in the Discovery series is comprised of a 13 year old Kentucky bourbon blend of 74% corn, 18% rye, and 8% malted barley; a 15 year old Kentucky bourbon blend of 78.5% corn, 13% rye, and 8.5% malted barley; and a 10 year old Kentucky bourbon made up of 75% corn, 13% rye and 12% malted barley (no wheat) making the difference.