You know what still has me a bit bamboozled is the fact that the Barnes 168 TTSX loads hit about 1 1/2 to 2" lower than the Fusions do. The 165 gr Coreloks and the 165 grain Interlocks hit to almost the same POI as the Fusions do , and it suprises me that the Barnes loads hit that much lower. Have read that the Fusions are generally loaded a little mild but they have been almost identical to most other 165 gr factory loads I have shot. Cant imagine 3 grains making that much difference or they are just that much slower.
The weight of the boolit has absolutely no bearing on where it will hit the target. Upon firing the barrel vibrates as the boolit is traveling down it, where the boolit exits the barrel in relation to this vibration is where it will impact the target. Thus a lighter boolit can actually hit lower on the target than a heavier one. This is why when we work up loads we search for the one load that exits the barrel in about the middle of the vibration cycle. As you add powder to the load you can see the groups opening and closing because of this phenomenon. Changing something as innocent as the primer can alter POI several inches. It changes the vibrations of the barrel. If you have seen the donuts that Sims sells for the barrel, this is to try and change the harmonics of the barrel. Same goes for the BOSS system on the Browning and Winchester rifles. As you move the BOSS brake out further it changes the harmonics within the barrel.
