Always verify what others say. No one can tell you that a particular weighed charge of black powder is best in any caliber. That's why loading with black powder is 'method' and not necessarily duplication like you find in a smokeless loading manual. When I use the correct method to load, I know that I have ended up with the proper load for that cartridge. Powder type, bullet, and brass may change, but the method remains the same.
Black powder is loaded by grains-volume.
That means if you take a volumetric black powder measure that reads '60 grains' for example, it is 60 grains volume, not necessarily 60 grains weight. Thinking volume instead of weight took me a little getting used to. With black powder and Pyrodex. I had to switch my focus to proper volume or black powder 'grains'. This is not the same as weight in grains of powder that you would weigh on your scales.