Goex actually makes a cartridge grade of powder. In the 45-70 use a drop tube at least 18 inches long to load slowly allowing the powder to compress. If using card or felt patch over the powder allow for that and fill to the point that you can just get the bullet in. I use this procedure for my 40-65. You might try one of the cartridge sites for more information. Basically with any cartridge and black powder you want the case full and the powder slightly compressed.