Marrakai:
Thanks for the reminder about the laws of physics. You addressed me and asked for information about a specific case. I responded as directly, factually and to the point (with due regard to the laws of physics) as I am able, and did not say anything about 'most cases', but only the facts I am aware of which seemed pertinent to your query.
In the specific case of your rifle, as described, the bullet which is giving unsatisfactory accuracy at ranges beyond 50 yards/meters is NOT sufficiently stabilized at the muzzle, Q.E.D. The actual cause of the observed performance should certainly be in the factors discussed thusfar (though it is possible that there is some defect in the barrel or its chambering and fitting which is contributing to the problem), and will therefore have to be sought by detailed examination of your rifle and the ammunition components and performance associated with its use. The two specific pieces of the puzzle which you could provide, and which I asked you for, (actual pitch in your barrel and bullet length/s) - a matter of a few minutes direct measurement - you have not given. So, on balance, and from my perspective, it seems that, on your end, the bull is still on its feet.
As for Bulldog's original question: that was answered, too, evidently to his satisfaction.
mhb - Mike