One of the main disadvantages of pirate pistols and other early firearms were inaccuracy. Problem is partly solved with muskets, as they were first sniping weapon of pirates. This weapon had very long barrel and it was not useful in close encounters in boarding attacks. So it was used in different way, adding a new dimension in pirate fights. In typical ship battle, gifted shooter stood on platforms called fighting tops and shoot opponents from above.
Muskets evolved just like pistols from wheellock and matchlock to flintlock mechanism and they were generally fired from the shoulder. Unfortunately, musket is not so easy to handle and they were very expensive. The buccaneers preferred musket more than the Golden Age pirates as it proved to be handful in many of their actions like attacks on rich Spanish towns.
Musketoon is most used version of musket by the Golden Age pirates because it was designed for boarding and other close encounters. This weapon was lighter then musket and had shorter barrel making it a lot easier to handle. They were not so accurate, but inflicted a large amount of damage.
You can imagine blunderbuss as little cannon held in hands. It is indeed a firearm with power of cannon, causing mass damage in wide area and it was still wearable like musket. Just like any other two handed guns it was fired from the shoulder. Of course, blunderbuss was neither accurate nor wide ranged. Unique wider shape at the end of the barrel was intended to even more spread the shot. Bluderbuss was much shorter than musket and it was very good defensive weapon, especially in repealing pirate attacks.