As Gerald says the attachment mechanism is completely different and thus they are not interchangeable.
But as far as contours go, what we need is for someone to send in one of their Quad factory sporter barrels to Lilja so Dan can duplicate the contour. I have done this before for the Tikka M595. You send Dan the barrel and $30 and he does a custom contour program for the factory barrel. Once the program is in his machine it stays there forever and is available to others. I would do it but I need my factory barrels on my Quads for the spring/summer shooting season.
IMO the HB and Sundberg contours are too heavy for the intended purpose of the little light weight synthetic Quad. I suppose one could order a Finnfire sporter contour for their Quad but I am not sure it will fit perfectly.
So if any of you Quad guys have a spare factory sporter barrel laying around do us all a favor and send it into Dan and let him use it to create a factory contour program.