Which type of powder can cause serious injury if used in a muzzleloader?

Using modern smokeless powder in a muzzleloader can lead to serious injuries due to the significant differences in their intended applications and pressure limits. Muzzleloaders are designed to operate with black powder or substitute powders like Pyrodex®. These types of powder burn at a slower rate and produce pressures that are within the safe limits for muzzleloader firearms.

In contrast, smokeless powder is formulated to burn much more efficiently and at a higher pressure. When used in a muzzleloader, it can create dangerously high pressures that the muzzleloader is not designed to handle, potentially leading to catastrophic failures such as explosions, which can result in severe injuries to the shooter and bystanders, as well as damage to the firearm. Therefore, it's crucial to only use the types of powder specified by the manufacturer for any given firearm.