Was Master Gunner an actual naval title?

If the sailing master handled navigation, was Master Gunner the corresponding title for the gunnery specialist?

Yes. Master Gunner was an actual title for the senior gunnery officer.

The follow-up extends the earlier discussion of the sailing master's navigation role. Master Gunner was an actual title for the senior gunnery specialist. The terminology shows how older ships identified important technical authority through specialist appointments as well as commissioned command. The brief passage establishes the title and field, but does not attempt a full account of the holder's rank or duties.