I just picked up a 243 thumb hole laminate,bull barrel,a couple of months ago,,when I first shot it,,it was all over the place,a lot of vertical stringing,,then checked and modified a little,,according to FAQ section,,and that dramatically improved accuracy,,around 2'' at 100 yards,,,then took it to a gunsmith to check my muzzle crown,,,he said the crown is fine,,just keep shooting it,,it will get better,,and low and behold it has improved,,,I run the federal 243 80 grain psp,,it's relatively cheaper,,,to use for barrel break in,,,last time at the range i was doing a little over 1'' at 100 yard's,,,,might try experimenting with some different ammo soon,,,but not till I get some venison though,,,it's shotgun week here now,,,then bow again after