From their website:
Cask Strength Releases
Our Kentucky Straight Rye Whiskeys are offered as a Cask Strength release. Once our traditional sweet mash process is distilled in our column stills we enter the barrel at the lowest entry proof we know of in Kentucky. We barrel at 100 proof and 105 proof to highlight the balance of the distillate and alternate solubility expression we get from the barrel at a lower proof. We also barreled at a gradient of proofs between 100 and 120 proof for our first few years before settling into 100 and 105 proof. This is the reason you will find releases of our cask strength Rye varying in proof.
Our three-grain recipe is 56 percent rye, 33 percent corn and 11 percent malted barley. Our rye mash bill is one we created for a broader balance of flavor to offset the typical high ryes commonly found. We use Kentucky-grown Heritage rye from our local KY Proud farm. We enter the new, air-dried #4 char, 53-gallon barrels at 100 proof and 105 proof for our Rye Whiskey and age until maturity in our barrelhouse. We age our Rye Whiskeys on the upper floors of our rickhouses for a minimum of 4 years with regular expressions expected to be between 6 and 8 years of age