Experimental Blowgun Dart Cup

The idea behind this dart cup is to keep the dart more horizontal as it accelerates out for the gun. Normally, the dart tips toward one side, with the head rubbing the inside of the barrel on the way out.
This should keep the dart straight, prevent air from escaping past the dart, and has the side-effect of acting like a proper fletch in mid-flight.
I have OpenJSCAD available on request.