Dealer opens 4D vulnerable - your bid

[paulg]

I must admit that it never entered my mind to find 3♦ in the responder hand because you should raise with that holding. You could easily buy the contract for 5♦ undoubled or push 4th seat into making a high-level guess without much to go on. It is just barely possible to find slam, I think maybe with

4♦ PASS PASS 4NT (two lower unbid)

PASS 5♦ PASS 6♥... but really it's kind of a stretch.

 

And making 13 tricks with the hands is kind of lucky. Not only do you need hearts to behave, but you also need to find the Q♠ in the pocket.

I disagree. As responder you know that the opposition can almost certainly make a slam and bidding 5♦ may be the one way to push them into it. Even if they double it is likely to be -800 so might as well let them try and play in game. This hand shows that they might well find it difficult to express both their distribution and values.