Very, VERY interesting. You will find a bunch of discussions here on this forum regarding Jamestown glass reproductions. These may be a Jamestown item possibly, but they are not quite like anything I have seen.
It would appear both bottles are machine made what with the mold seams and the markings on the base. However, I am thinking these may be modern wine bottles that were put in the kiln and heated and then reworked....that is reshaped with paddles, a hand tooled lip was applied and then finally the glass seal was added.
These are definitely modern pieces which are meant to imitate 17th or 18th century black glass.
The form here is more or less a chestnut shape - am not sure there are any known examples of sealed chestnut-shaped bottles.