Well folks, the powder horn is back with a new spring, a work as good as it could be.
Maybe what i now found out answers some (all?) questions.
The horns are indeed divided my the middle, not one deeper than the other. And,
importantly, the hanging rings are placed in a way that, the device does not bend down when hung but ergonomically around the trunk, so that the position of either end is not arbitrary but forcingly with a determined
front and
back meaning that, whatever is filled in each container always has the same relative position. So, considering that horns did not have measuring devices in their spouts, it is possible to fill one side with gunpowder and the other with small shot, to pour out in a free flow, doses by estimation. And the user would hardly confuse them as, whatever he wanted to fill in each one, is always in the same side.
No need to tell me i am brilliant; i know i am
.
.