Eventually I want to advance to the point where I can comprehend at least 75% of what Bob (rsterne) says!
The OD on both measure 0.865". The QB wall thickness is about 0.054". I'll compare the wall on the XS60C the next time I'm changing cartridges.
Now if I were going to make it a PCP and pump it up the tube to 3000psi, I would proceed with much caution.