A statement in the Vihtavuori manual caught my eye. It sayed, "The Poisson Effect is usually very small. The forces due to the Magnus Effect are also small when the trajectory is flat. With a big shooting angle, however, it may happen that at the top of the trajectory the Magnus Effect is bigger than the Spin Effect and the bullet will move to the left." Now after reading this it makes me wonder how "big" of a shooting angle does it take to move the bullet left instead of right as I had believed it would in any case?

I was thinking at 1500 yards or more the angle would be high enough to see this if it existed to any degree. I don't know if Vihtavuori was basing this on actual flight tests or merely program predictions. Warren, were you able to observe this on the tests at Yuma or in fact the opposite. If one used the formula for spin the spin drift S1 gave us, does it need to be modified when the bore reaches a certain angle at a given range? Is the angle of uphill or downhill shooting at extreme range in keeping with this also? If there is a shift of flight back to the left this formula for spin drift would likely be flawed, but to what point and at what range or bore angle or both is it and how do come up with your conclusion on this?