I only copied the chart for TC9Ball Its from Prather so I would go to their website and straighten them out. I heard they make cues also
That might be true, but it's still wrong

If you do .312" for a regular 3/8-10 pin, like a McDermott, that's gonna be a very loose fit indeed. For a 3/8-10 Modified pin, it's only 4 thou off, but still the point of that pin is to live thread shafts with an accurate minor, so you get a perfect fit.
All that being said, why not spend a day in the shop, take a few shaft blanks that didn't meet expectations, cut them into 2" and 3" pieces and play around with the minor and tap H grade and see what you think works best, when you are happy, write the specs on the side of the piece and save it for future reffrence.