Bass
Those are good points and they and any more we come up with are certainly part of a final object of accuracy. Air flow based on bullet rotation does cause the bullet to divert; we refer to it as drift. However it is a long range phenomena with little measurable effect at the close range of 100 yards. What effect there might be from drift causes the bullets to move in the same direction and results in a POI shift of the group. It does not result in dispersion of the group as the effect is the same on each bullet fired.
Again let me remind everyone; I am not seeking the most accurate load. I am only isolating those factors which cause inaccuracy at higher velocity. The initial objective is to determine the existence or not of the RPM threshold. If in the latter portion of this test I isolate a factor that improves accuracy at high velocity that will be enough. I will not attempt to determine just how much of that factor gives the ultimate accuracy. That right now is beyond the scope of what I am doing. I. E. if I find harder alloy tightens the group I will not proceed to find out which hardness tightens the group the most. It is not pertinent to this test “how much” but only “if it does”.
If anyone cares to take what we find here using actual tests to isolate those accuracy factors and adapt it to their loads to find the most accurate loads for their rifles at high velocity they are more than welcome. We will have accomplished something by furthering our knowledge with facts. If they take what we find here and decide they can’t get to high velocity with the cast bullet/loads they’re using and want to pursue a custom bullet such as your LBT then we’ve accomplished something.
Larry Gibson
BTW; I am not 'focused" on "outta balance" bullets. All bullets are "outta balance". All bullets, cast and jacketed, when fired are "outta balance". It is why we shoot groups instead of all shots into one hole. What I am focused on is why cast bullets only shoot well to a certain point at medium velocity. I am focused on why there is a threshold that is difficult (I did not say it can't be done) to get through to have equal accuracy at high velocity. The evidence points to RPM as the reason. If we are going to shoot with equal accuracy at high velocity/RPM with cast bullets then what are the things we can do to negate the adverse effects of that RPM.