It won't be the tail wagging the dog, starting with a powder and bullet and looking for data. You have to have the powder that matches the limited data. I started with Brian Pearce's articles and have tried a number of loads. With bullets at 210-215 grain I favor Power Pistol with 7.4 for lead and 8.0 grains for XTP. My heavy load is 13.0 grains of 2400 and Xtreme plated or XTPs. The gun is a 3 inch GP100, converted from 38 Special by Clement Custom Guns.