Why powder is the only kind that should be used in a muzzleloader?

Powder, specifically black powder or its modern substitutes, is the only type suitable for use in muzzleloaders because it is designed to ignite and produce the necessary pressure to propel a projectile efficiently. Other types of propellants, like smokeless powder, can create dangerously high pressures that exceed the design limits of muzzleloader barrels, leading to catastrophic failures. Additionally, black powder has a slower burn rate, providing a safer and more controlled explosion for the shooter. Thus, using the appropriate powder ensures safe and effective operation of muzzleloaders.