1♦-1♠
3♥
or
1♣-1M
3♦
The hand that raised this question was:
None of the pairs with the N-S hands bid the slam. In our K-S style, the 2S bid shows 4 card support and the equivalent strength of a strong 1NT open. A jump to 3S instead would have shown a stronger hand than North had. Even if North stretches to jump to 3S, and South stretches to que 4D, it is unlikely that we would get higher than 4S.
The stiff H in North is the key to considering a slam with only 24 HCP. My thought (after the hand) is that a reverse by North would be a one round force, so a jump reverse would not simply be a stronger bid, but would have a different meaning. A H splinter seems right to me, but it could be only an invitational raise to 2.5S and not be a game force. North could use the jump reverse as a splinter that invites to game if South has no wasted values in Hs. Then North could pass if South bids only 3S. Conversely, the jump reverse would set Ss as trump, so 3NT by South would not be natural to play. Instead, South's 3NT would show at least mild slam interest, and would ask North to que on the way to 4S. If we had discussed this meaning, my preferred auction would be:
1D-1S
3H-3NT
4C-4D
4S-4NT RKC to 6S
Does anyone have a better way to bid this slam, or have a better meaning for a jump reverse?