I toured Jim Beam, Clermont, on Friday and learned something interesting. They are now bringing the different expressions off the still at slightly different proofs.
Originally, they made two bourbons, regular Jim Beam and high-rye Old Grand-Dad. The Old Grand-Dad juice was used for OGD and Basil Hayden and the JB juice was used for everything else. For the small batchers, except BH, a barrel didn't become Baker's, or Booker's, or Knob Creek until it was dumped.
Then they started to do wood management. It was the same juice off the still, but they barreled and put away according to brand, so the whiskey was Knob Creek (for example) as soon as it went into the barrel, and it was put away according to where it would age best in nine years, into a whiskey with the Knob Creek profile. Ditto for the other expressions.
Now, not long ago, they have started to actually bring the spirit off the still at different proofs, according to what brand it's going to be. Bookers and Baker's come off at 125 proof, Knob comes off at 130, and Jim Beam white and black come off at 135. Booker's and Baker's have no water added and go into the barrel at 125. Knob and Jim have water added so they too can go into the barrel at 125.
Ditto OGD/BH, which comes off at 127 and gets diluted slightly to 125 for entry.
So what? Lower distillation proof means more flavor.