Some people will argue with me about this, but for general, normal, everyday use, muzzleloader bullets/balls should be cast from pure, soft lead of around 5 on the Brinell hardness scale. Even regular wheelweights, as soft as they are, tend to be too hard. The problem with the harder alloys comes when loading. Harder stuff will result in cut patches, or conicals like a MaxiBall that arehard to start, and almost need to be pounded down onto the powder.

Yes, harder alloys can be used if cast undersize for your bore and shot with thick patches, BUT the patch will not grip the harder balls sufficiently to ensure they spin, and hard projectiles will not swage up (obturate) at ML pressure levels, so accuracy cansuffer. Perhaps up to 50 yards or so, such projectiles will shoot well enough to kill deer.......