Energy figures mean very little. All that is is a number based on the velocity and the weight of the bullet. It tells you a whole lot of nothing. With muzzleloaders, heavier bullets are better. I would never go less than 300 grains and up around 350 is better. The only exception would be the Barnes bullet like carpsniper uses, and that's because it is 100% copper. So even though it's light at only 290 grains, it's more like a heavier bullet in a lead version. The real advantage with lighter bullets is the reduction in recoil. If you want good penetration, a heavy bullet beats a light bullet every time.