Sure looks like a patilla miquelet lock to me eyes. A lock made in such places as Eibar Spain. These are from the early 18th century. The blunderbuss style muzzle flare reflects perhaps maritime use. It was commonly known that British RN officers had similarly muzzle flared pistols to discourage mutinious intentions of his crew. Maybe this one resurfaced in Florida, Mexico, or perhaps another Central American country? Really nice catch Tokguy! Oh the stories from this thing, we so wish it could tell us!! If I was yourself, I too would choose not to part with this little jem.
But thank you for sharing the fine photos friend.
Edit: The NRA museum has a very early Spanish miquelet blunderbuss that is the oldest piece found in the colonial Americas.
It was supposedly relocked in Mexico (it is believed by the aritsan style of the hammer & frizzen) and the style of it, is kind of similar to yours from my untrained eyes IMO. I'm no expert, but I'm just putting this out there guys.