so it sounds like you didn't have the similar issue with your Proof CF barrel? POI of my 6.5 cr SS barrel can shift ~1 MOA to the lower right after 3 -5 groups of 5 rd shooting, and the group begins to open up. It's also sensitive to the MB, POI shifts 6MOA without MB, very strange.I initially had some concerns with my groups opening up under high heat after conducting a 15 round mag dump and then tried to shoot for groups. But after my last several range trips in colder weather and using a heat shield the group expansion I was experiencing was due to mirage. All barrels are going to open up as the heat increases, I'm not seeing the PR barrels act any differently. I personally don't care for the contour Proof uses on their SS 6.5CM barrels, it's too light I'd much rather have the old M110 Profile they first used and still do on the .308 SS barrels.
I agree the contour of Proof SS barrel is too light. I didn't do my research very carefully and anticipated it to be just like their CF barrel contour, maybe this is why it acts like that? not saying Proof SS is bad (cold bore can still do 1/2 MOA), but so far it is just not what I need. The barrel has the potential, but the light contour maybe the issue here.
I m looking for an AR10 setup that can shoot up to1000 yards with good accuracy after reasonable amount of shooting, and I don't really care about the cost or weight. If their CF barrels are not that temperature sensitive, I m considering getting one.