A Winnipeg area shooter by the name of Trent Procter who works for Manitoba Hydro was sighting in his Savage muzzleloader rifle and nearly lost his hand. This happened on October 24, 2009. Luckily, he had his hand on the scope instead of the forearm when this happened. (Incidentally, the Savage is the only muzzleloader that is supposed to withstand the high pressures of smokeless powder.)

I don't know if this failure happened due to a defect in the rifle itself or if the shooter perhaps didn't properly seat the projectile against the powder firmly. This is VERY important with any muzzleloader, especially when shooting black powder.