I went through this last year when I tried a new choke. The new choke shot 6's best, the old choke shot 4's best. I really hoped 5's would pattern best, but they weren't very good with either choke. Ended up sticking with the old choke and #4 shot.

I've heard a few stories from buddies and aquaintances about wounded toms, or clean misses followed by "I don't understand it, my pattern is great and my crosshairs were right on him!" In every case, #6 shot was used. I'll admit that may be a coincidence, and a few "after the fact" stories hardly merit any statistical significance. I've also seen gobblers poleaxed at a pretty good distance by #6 shot.

Maybe I'll print this thread, and show it to my wife as evidence that I need to keep buying choke tubes 'till I get one that patterns good with #5!