Why does POI change between different bullets? Most of my rifles have little or no change. For instance my 20VT will shoot Nosler, Hornady, and Sierra bullets within 1/4" of each other. My custom 260 Rem will shoot everything into the same spot at 100 yards no matter the weight, shape, or make of bullet. However, my wife's 308 win (Douglas 1/10 generally about 1/2MOA @ 100 yards) will shift 8-12 inches left right up down. 150 Hornady Interlock SP shoot 10 inches right. 150 Sierra Pro Hunter Flat Point 10 inches high and a couple to the right. 150 Sierra Prohunter Spire Point dead center. 150 Sierra gameking 6" left. Speers are low. Extreme spread left to right is 1 1/2 FEET. All bullets group fantastic though just got to adjust the scope is all. All loads tested for accuracy noads ect. Barrel cleanliness or fouling is not a factor here. I'm familiar with barrel whip/harmonics ect, but never really though of a barrel whipping in a circular motion. As I ponder this kinda makes sense as it is a savage 99 and has a very small shank of minimal diameter that could be more influenced by a tight twist. This is a featherweight barrel, 22". Ya ya just shoot one bullet I know. Probably nothing could fix the situation, just trying to understand it better.