I printed this one and this one. They are both very reviewed and loved. I Used 0.6mm nozzle on a Bambu X1C with PLA and a 0.18mm layer height.

Both fit the Bowden connectors threading in. However when you want to send filament through it got stuck on the way out. It's tough because I cant exactly see what's happening. There is a hole through the output side, and it is big enough for filament (I have checked by forcing it through and by sending it through in reverse).

It's like these designs do not funnel the filament to be aligned with the outgoing connector if the filament is at all bent/shaped/curved which realistically it is going to be.

Am I doing something wrong? It feels like maybe the design should have like funneled/lofted the inner tube down to the exact size of the outgoing spot so there is no sharp edges to snag on.

Do I have a false expectation about how smoothly these should work? Is it difficult to get the filament to make it through for you too?