There is a game called Dungeon&Fighter that meets your requirements, it has muskets available for gunner classes you should try the game out even though its a foreign game, there is a official thread in the korean&foreign games forums go check it out. also here are some videos for you to preview.
Musket ranger
Musket spitfire vs Revolver ranger
Musket General (spitfire)
Ceres,are any one of those vid you posted,posted by you? LOLOLOLOLOLOL....what kind of........leaves the FPS on while recording.