3 NT Opening

Not Strength Showing. We play 3 NT opening bids as "gambling" rather than strength showing. It's either a good try for game or a good pre-empt.
Reasoning. A Standard American strong 3 NT shows 25 - 27 HCP and comes up very seldom. We make use of the 3NT opening for a more frequent hand pattern because we have plenty of other ways to bid hands with 22+ HCP.

It's called the "Gambling 3 Notrump opener".
A Gambling 3 NT opening could mean either of two situations:
  1. "I have a long, solid minor suit (usually 7) with stoppers in two other suits."
  2. "I have a long, solid minor suit with no stoppers anywhere outside my suit." In other words, "I have a preemptive bid with a long solid minor suit".
The Choices. The first situation is a one-handed gamble. If the defense doesn't lead the unstopped suit, opener will make or come very close all alone. Unfortunately, partner is in the dark with no way to find out where the outside strength is. Some pairs play it this way, however.
Our Choice. The second choice makes more sense to us, so this is the way we play it. If responder is quite weak, you've made a good pre-empt. Virtually no opponents will bid well over a 3NT opening.

Responses. Partner can pass with 2 or 3 stoppers or bail out to 4 Clubs with a weak hand. Opener will then correct to 4 Diamonds if that's his long minor suit.

Rarely, responder can bid 5 Clubs with good support for both Clubs and Diamonds, with opener correcting to 5 Diamonds if necessary.