Its hard to say exactly but the USN had those long flight decks and fast carriers so they had considerable leeway for increased TO weight. However, I've run accross crew reports that indicate that performance was somewhat less than the SAC data indicates.Thank you, I know it was changed, what I don't know is when (before Midway) and how/why.
They did some calculations and figured the plane wouldn't break at the higher weights or did test flights or just figured that after some of the fuel burned off everything would be OK?