What type of black powder is used in large muskets?

The correct choice is related to the specifications of black powder granulation used in large muskets. Fg black powder, being the coarsest granulation, is suitable for larger bore firearms, such as muskets. This type of powder burns more slowly and produces a significant amount of gas, which is necessary for effectively propelling larger projectiles over longer distances.

In contrast, finer grades of black powder, such as FFFFg or FFFg, are typically more suited for smaller firearms or applications where a quicker burn is desired, such as in pistols or priming charges. The medium grade, FFg, could potentially be used in rifles but does not provide the same efficiency or safety in larger bore muskets compared to Fg. Thus, using Fg ensures the musket functions properly while maintaining safety and performance standards.