Greetings, blackjack community.

I'm a blackjack enthusiast, learning the secrets of this marvelous game. Recently I read an excellent and entertaining book written by Olaf Vancura and Ken Fuchs about Knock-Out card counting system. Currently I'm reading "Modern Blackjack" by Norman Wattenberger. I started counting cards for two to three hours a day in my house and I intend to give it a try at our local casino in Montenegro after a month or two of intense practicing.

That being said, I'm eager to discuss with experienced advantage players the differences in K-O playing deviations (18 Preferred), which are necessary under the house rules in European casinos.

1. Doubling down is only allowed with hard totals of 9, 10 and 11, which automatically rules out two of 18 Preferred indices: doubling down 8 vs. 6 and 8 vs. 5.

2. Under ENHC rules one should never double down hard total of 10 or 11 if the dealer's upcard is 10-valued or an Ace. Am I wrong to assume that rules out three more indices: doubling 10 vs. 10, 10 vs. Ace and 11 vs. Ace when the running count reaches the pivot point (+4 regardless of the number of decks), reverting instead to the basic strategy and hitting as a correct way to play those hands?

3. In accordance with the recommendation of the authors of the book to completely omit category C plays in 4D, 6D and 8D games, that leaves us with only eight strategic plays in shoe games (18 minus 5 C entries and 5 aforementioned dictated by ENHC rules), and 13 in single and double deck games. Undoubtedly, that will make it easier to remember the deviations, but what is the impact on player's EV?

I will write down the deviations as listed in the book:

Insurance - side bet becomes profitable when the standard K-O running count is greater than or equal to +3.

A entries (A = pivot point, always at +4 or higher):

16 vs. 9 (stand)
15 vs. 10 (stand)
12 vs. 2 (stand)
12 vs. 3 (stand)
11 vs. Ace (double down in American blackjack)
10 vs. 10 (double down in American blackjack)
10 vs. Ace (double down in American blackjack)
9 vs. 2 (double down)
9 vs. 7 (double down)
8 vs. 5 (double down if allowed, otherwise hit)
8 vs. 6 (double down if allowed, otherwise hit)


B entries (B = key count; SD +2 or higher, DD +1 or higher, 4D -1, 6D -4, 8D -6):

16 vs. 10 (stand instead of hit)

C entries (C = initial running count; SD = 0, DD = -4. To be omitted in shoe games):

13 vs. 2
13 vs. 3
12 vs. 4
12 vs. 5
12 vs. 6 (every hand hit instead of stand in those situations).