I shoot a 6mm/284 Rem 700 with Shilen 1/12 twist barrel. Shilen and everybody else says that you can shoot up to an 85gr bullet in this twist which I knew when I put the barrel on. The 58gr Vmax will shoot 1/2" at 200 yards and 85gr Game Kings with shoot 1" at 200 yds. I tried to push the envelope a little and tried 90gr Bergers and they won't stay on the paper at 200 yds. The ones that print are leaving a round hole. My question is why? I expected the groups to open up some but not to that extreme. I fully understand that this twist obviously won't stabilize the bullet but why with only a 5gr increase?