I ask this because I have had issues with this myself. I did find out that one of the factors is the TKO. I'm extremely careful when I fill the gun not to touch the TKO. I you move the position of the TKO ever so slightly, Your POI will change.
I also added o-rings around each barrel band and that has helped a lot. I'm getting a new stock and I week wondering if I should move the back band near the breach.