Turns out the gap is just because of i forced the feeder too much during my tests and bend the tip. Doing it on a brand new jinhao gave perfect results. You can apply also hot air to the nib with a heat gun or hair dryer while squeezing with pliers or vise. I squeezed the nib and the drill bit together on a vise and applied some hot air. Now the zebra g is on a perfect fit. And the flow is also good, on a jinhao 750 i dpn't even have railroading.
Turns out the gap is just because of i forced the feeder too much during my tests and bend the tip. Doing it on a brand new jinhao gave perfect results. You can apply also hot air to the nib with a heat gun or hair dryer while squeezing with pliers or vise. I squeezed the nib and the drill bit together on a vise and applied some hot air. Now the zebra g is on a perfect fit. And the flow is also good, on a jinhao 750 i dpn't even have railroading.