Is it just me, or do others have trouble understanding the 100 psi delta group improvement? It seems that you have used that 100 psi with the first shot so the rest should look like the 2900 psi group? Call me silly but I think there are other factors at work LOL. Maybe try tethering at the lower end of the fill pressure to see if the groups open up?Anyhow, we are learning and learning some more with these barrels; what works any why. There seems to be no absolutes when it comes to twist, I'm beginning to believe barrel quality is the primary factor in accuracy. Good stuff Cedric.Tom