First off, yes, contact can feel bouncey/bumpy while you are learning technique. With practice it smooths out.
It seems that you are having trouble rotating from neck wrap to halo.
Try starting with a halo, rotating 180 degrees, and ending with a neck wrap. This will get you used to pivoting as the staff wraps around you.
Alternatively, if you have a good snes, you could enter the neckwrap from a shoulder wrap, this gives you more time to feel when to turn.
Also are you attempting to do this continuously? If you are, stop, and take it slow. all you are going to do is start the wrap/roll combo, rotate 180 degrees, completing one halo and one neck wrap.
Finally, (and controversially) try not spinning in plane. Try the trick on a 45 degree angle. it should be much easier and smoother. from here you can work towards vertical.
Ultimately it comes down to practice. Get off HOP and go practice.
Hope this helps.