Doubling with a Blackjack

When I was in Vegas for the marathon I played a lot of the $3 3:2 game at Circus Circus. I was having a blast chatting up all the strange sorts that came to the table, and the Heinekens were going down easily. In the course of the day a couple of guys got into a conversation about doubling down with 21. Only the dealer said she had seen it, while the couple of us at the table with general knowledge of basic strategy discussed the merits of it versus various up-cards. Sure enough, two hands later I staring at an Ace-Jack with the dealer showing a six. I put the second stack of chips next to the first (for a total of $6 on the hand) and take the second card, a six. Sure enough, dealer draws to an 18. The incident at least made for fun banter for any future blackjacks that came my way.

Anyways, my question is there any situation (including counting or a 6:5 game) where it could be advisable to double on 21?

Dan Y.

I think this play is no longer allowed in many places, but please correct me if I am wrong.
I think it is a valid move in the final rounds of a blackjack tournament, for example, if you are a little behind and covet some extra cheques.

Quote: dtyst1

Anyways, my question is there any situation (including counting or a 6:5 game) where it could be advisable to double on 21?

It's rarely allowed. But even when it is, it's not a good play, even if the blackjack pays 1:1.The risk of ruining a winning hand is too high. You don't even double on A+9 and rarely A+8.

Post-split there is no blackjack bonus and you are allowed to do it (not always), so it is a good play at very high count. But I don't even remember the index, you'd never do it anyway. Only applies if you're allowed to double after split, of course.