Besides OKFC05's comments you need to read Hodgdons remarks about Trail Boss. TB must not be compressed! When loads exceed approximately 90% of available space in the case this powder becomes quite erratic, with sometimes extremely high pressures. While loading for my Italian Vetterli-Vitalli a few years ago I got one batch that was basically a full case, not quite, but close! If you are not familiar this is a black powder military rifle in nominally 11mm. Pressure was high enough with one round that the cartridge case was destroyed and had to be driven from the chamber! No idea what the pressure was, but if it had been only slightly higher the case would have failed, the rifle probably destroyed, and I would likely have been severely injured!***
You can push the published data with many powders with no serious consequences, if any, but Trail Boss ISN'T ONE OF THEM!!!!!! Don't do it. Almost any other powder (Literally any!) will give better performance than Trail Boss. If you don't want full magnum performance use Unique, Universal, Power Pistol, BE-86 etc. It will be cheaper than Trail Boss too!
*** Note: I have been loading for nearly 60 years, have never blown up a gun or damaged one, and have often pushed the limits of published data very far. Forget Trail Boss except for using published data, or in loads that do not exceed 70% of available case volume, just as Hodgdon recommends. The story above is my own experience, not "Something I saw on the Internet"! Heed manufacturers warnings with this one.