I'm wondering how difficult it would be to install a Ruger 77 barrel onto a PF Winchester. From my small bit of checking, the Ruger barrel is .998 x 16tpi and the Winchester is 1.00 x 16tpi. Now I know it is not a simple screw in but is there any difference in the threads ?

Barrels will interhange; thread length and diameter is the same; check headspace; I just checked one of each. What you have to make sure of is that the chamber depth is the same. I just screwed a Ruger 223 barrel onto a M70 action; headspace was perfect and even the markings lined up (blind ass luck). Check the headspace but you might be lucky.