Join Date: Sep 2008
Location: Bavaria, Germany - the center of 15th and 16th century gunmaking
Those little amorphous dark pieces may be just any kind of stuff.
As I said: no black on the finger - no traces of powder.
Remember black powder was not grained but fine meal powder (dust) in that period of time.
You may be interested to learn that the horizontal section of the iron base mount of your flask is very similar to that of the Ottheinrich flask dated 1552, so I would plead for assigning a date of 'ca. 1550' to it.
In the Von Morenberg sale of 13 Nov 2010, your flask was marked sold for 680 euro plus commission (Asta 41, lot 667, described as '17th c.') - see attachments.