thinking Matt doesn't know much about MLers fellas. Think he is comparing ML bullets to center fire.

Matt, Muzzleloaders don't typically reach high velocities so you want a big heavy bullet to penetrate. With the speeds of your typical center fire you can have much lighter bullets and still achieve adequate penetration. Momentum is key to muzzleloaders. Nowadays we have better powders to attain higher velocities but for the most part we are still in the 1700-2000 fps range so you need to have that size and weight for momentum.