Ottoman/Balkan Grease/Bullet Container

[kahnjar1]

There has been a lot of discussion as to what these SMALL containers were used for. The one I recently bought has a dry grey coloured powder residue inside.
I believe that this is flint dust.
1.Not likely to be powder residue due to fact the top does not seal tightly. Also the residue will not burn.
2.Not likely to be from lead balls as that would leave an attached colouration, and not a loose powder, and the balls would need to be VERY small.
3.Not likely grease or greased patches, as it is dry.
A container of this size would hold several flints, even those larger ones for muskets, so perhaps the use for these is solved??
Comments please.
Stu