Reading up further on what they've done for the Sinatra, apparently the interior staves or some of them were grooved at regular intervals to expose more (uncharred) wood - I saw a picture and it looked like a an evenly ribbed piece of wood with the ribs black and the exposed wood white between each rib.

Now, to me, this surely has the effect of reducing the red layer unless extra ribbed staves were suspended down into the barrel and the regular barrel staves were charred in the usual way. Since it is whiskey not bourbon, not all the cask has to be charred in the usual way although they may well have done it that way. I understand too these special barrels were mingled with Old No. 7 so the Sinatra whiskey is not purely from the jerry-rig system.

Anyway, the bottle I had today was superb. I may buy it now, but I hope the next one is as good as the one I tasted today..