Feltwad,
What period in history have you found that the "Irish" and "English" designations took hold?
The powder and shot flask has we know today took hold from 1780 onwards the period of John and Joseph Manton .One of the early makers of flasks was Frith ,later firms such has Dixon ,Bartram and others followed in the early 1800,s.
Sheffield was the main town for the production of powder and shot flasks most powder flasks were made of copper in different designs and sizes,also tin and pewter,some of those made of tin were covered with Morrocan leather .
Feltwad
A Flint Lock will not secure a chicken house door