Progressive Rubber Bridge is a variation of the standard progressive game. It follows the same methods of progression and change of partners described in the preceding rules, but the scoring is somewhat different.
Under this arrangement it is preferable to play six or eight deals to a round, or to fix the length of a round by a definite time limit – 30 minutes for example. If the length of a round is determined by a time limit, any deal that has been started before time is up may be completed, but no new hand may be dealt.
Rubber scoring is used. As many rubbers as possible are completed during the allotted time. A rubber completed in two games carries a bonus of 700 points. A three-game rubber carries a bonus of 500 points. If a side has won one game toward a rubber and the other side has not won a game, 300 points are allowed for the single game won. If a rubber is unfinished and one side has made one or more part-score contracts in an unfinished game, but the other side has made no part-score, a side with a part-score adds 50 (or 100) points to its score.
Vulnerability is determined only by the state of the score. A side is vulnerable when it has won a game and remains vulnerable until the conclusion of that rubber. However, vulnerability lapses at the end of a round, and a new rubber is started at the beginning of each new round.
At the end of a round, each player enters on his tally only the net gain or loss–not the total score. At the end of the session these net gains and losses are totaled, and the player's final score, plus or minus as the case may be, is entered at the bottom of this tally.
Any time a player holds exactly 31, he may "knock" immediately, and wins the pot. If a player knocks before the first round of exchanges have begun, the showdown occurs immediately, with no exchange of cards. After the pot has been won, all the players put in chips for the next hand.