Think Bacardi 151. But also don’t, because that’s kind of the worst, and not really the same thing.
The only reason I bring up 151 is because you probably know what it is, and because its ABV, of 75.5%, is well out of the range of what is typically sold, and that’s kind-of-but-not-really what cask strength means. So, like, 151 was barrel proof/cask strength before it was cool…thematically, anyway.
Barrel proof or Cask Strength: the ABV (alcohol by volume) of the spirit that’s typically seen in the alcohol while still in the cask for maturation, usually between 60-65%.
Also, barrel proof/cask strength is not meant for super-powerful shots or a cheap, efficient intoxication for adolescents and (wo)man-children. Here are a few more legitimate applications to overproof (which is, annoyingly, yet another name that can mean “higher than usual ABV spirit”).
One point of it is more in the realm of flavor balancing in a cocktail. As there hasn’t been much/any dilution in process pre-bottling – where most whisk(e)y is diluted to the 40% to 45% range – it has a much stronger flavor profile; meaning,
1.) the less flavor you’ll lose/obscure when you mix it up with other things, and
2.) the longer your whisk(e)y can stand up in a drink on the rocks (you won’t be left with a pool of vaguely whiskey-flavored water if you keep it too long).
Another is simply personal preference: 40-45% dilution has come to be more of a generic stronghold of the ABV realm; however, the flavor of the whisk(e)y will change at different points in its dilution spectrum. So as with everything else, it’s now (getting to be) more acceptable to drink it to one’s individual liking. If you’re tryna sip it neat at 60% abv, more power to you. Dilute to 50%? Sure, same deal. 49.8%? Okay, now you’re just being a tool.
Ready to try it? Some of the larger brands, below, can be found at your local alcohol store – though, if you find the section with these, you can usually find the smaller guys right next to ’em, and they’re certainly worth a shot. In all cases, be warned: because it isn’t diluted, or at least diluted as much, and often aged for longer, it’ll cost you a little more. But sometimes, and most times, you pay for the quality. Adults!
Bulleit Bourbon Barrel Strength
Elijah Craig Barrel Proof
Akashi White Oak (Just kidding! It’s $360 and I haven’t yet seen it in a liquor store)