I created a very basic gen 5 prototype feed, for ink fill test
only airchannel is applied (some omitted)
all other features not applied (rib, ink channel, etc.)

this is the side view of the test feed


air channel from converter is connected to the hole
the hole is drilled to the center of the feed


a long thin hole is drilled all the way to the aforementioned hole
drilling thin-long hole is not easy


this is the airchannel profile of the 5th gen ebonite feed
note, for the test i didn't put the upper airchannel on top
i placed it at the bottom for a quick testing


this is the ink fill video.
do note i had to film with the other hand
so keeping the converter vertically was not so easy
pilot Con-70 converter will not fill properly, if the converter is kept exactly vertical.
https://tv.kakao.com/v/438962160