Not to revive an old thread, but I found this while searching for an answer to my question about a Proof CF 6.5cm barrel.
What I was looking for had to do with using a suppressor in conjunction with a CF barrel. I am running, make that *was* running, a 22" Proof CF barrel in 6.5cm with either a Silencerco Saker 7.62 or Omega 300 suppressor. I said "was" since I have now removed the barrel after 125 rounds and will be selling it, have already ordered another Proof full stainless barrel to replace it. My issue was that with 5 different loads it grouped fantastically without a suppressor, but once one was used the groups were terrible. And there was a 1 mil poi shift with the suppressor below the unsuppressed impact point. I could live with the poi shift if not exactly pleased about it, but the groups completely opening up not so much. Tried 130gr Berger hybrid, 140gr Hornady ELD-M, 143gr ELD-X and 153gr A-Tip. While I might be able to find a bullet/powder charge that works, I do not really want to keep putting round after round down the barrel getting there and in my experience I have been able to work up a good load with normal stainless barrels in the past.
So long story short, without a suppressor it shot great with all of the loads I tried, normally .5 MOA or thereabouts. With suppressor they all opened up significantly, as in 1.5-1.75 MOA. So that was my experience and as such the barrel is going to be sold.