@THEIS Thank you for the file you sent me. (Or maybe I should say FU since I stayed up until 3 in the morning trying to digest it Friday night! LOL) It shed a great deal of light on the subject. After reading it I consulted with an old friend who is an aerospace engineer, and he helped put it into terms that I could understand.
@sandwarrior You helped even more by taking what he told me and condensing it into a nutshell.
Here are my takeaways from all this info:
1) Vaughn's definition of "coning motion" is flawed because it only considers the motion of the nose of the bullet and does not consider the motion of the tail around the CG. He also fails to consider pitch, yaw and exterior factors such as wind.
2) No rifle and bullet combination will EVER result in physically smaller groups downrange. That is to say that it is impossible for a five shot group that measures 2 inches at 100 yards to shrink to 1 inch at 200 yards.
3) However, as deflection and precession forces become balanced it is possible for angular dispersion to decrease. As this occurs the physical measurement of the group will continue to grow, but at a slower rate than earlier (and greater) angular dispersion would have indicated.
Now, for the most part I am not that bright (and I am certainly not a rocket scientist), so I will do my best to explain what I think this all means in common sense terms and apply that to my original question: Can a rifle group better at 20-300 yards than at 100 yards? Well, that depends on your definition of "group better". If you define a better group as physically smaller, e.g. 2 inches at 100 yards versus 1 inch at 200 yards then the answer is definitely NO.
However, if you are defining "group better" in terms angular measurement, or in simpler terms how well a group holds together then the answer in theory is YES. Here is why: Most of us (myself previously included) logically think that if a gun shoots a group that measures
one inch at 100 yards that same group will grow proportionally to
six inches at 600 yards, and if the angular measurement remains unchanged from 100 to 600 yards that would be correct. However, if as the bullet stabilizes the angular measurement decreased then theoretically a one inch group at 100 yards might only become a
three inch group at 600 yards.
Of course, the opposite can be true as well. As velocity and spin rate decrease bullet stabilization falls apart, so a gun could produce a super tight group at 100 yards, but the same gun/ammo combo could look like shit at 500 if the bullet starts to de-stabilize early as it travels down range. A great real world example of this would be an AR15 in 5.56 NATO that I own sporting an 18" barrel with a 1:9 twist. This gun is an absolute tack driver at 100 yards with bullets from 40-77 grains in weight, and I consistently shoot steal out to 450 yards with this gun using Beck Ammunition 55 grain VMAX rounds. However, at 450 with 77 grain Sierra Match Kings I cannot hit an IPSC consistently to save my life because that 1:9 does not spin that bullet fast enough for it to remain stabilized over distance.
So let's go back to the original question and consider it in the following hypothetical scenario:
Shooter A has a gun/load combo that consistently shoots 5 shot groups measuring 1/2 inch at 100 yards and just over 3 inches at 600 yards. This occurs because his combo produces bullet stabilization very early resulting in an angular measurement that remains constant over several hundred yards down range. Shooter B has a gun/load combo producing groups that are usually in the one inch range at 100 yards but that consistently stay around 3 inches at 600 yards. If I understand what I have learned from
@THEIS ,
@sandwarrior and my buddy correctly this is possible because he has a combo that results in the bullet having to travel further before achieving optimum stabilization, but, once his bullet stabilizes angular measurement improves significantly resulting in groups that grow physically larger down range, but that also have less dispersion than one would logically expect based on his group sizes at close range.
I guess that all of this means that if a persons definition of "grouping better down range" means tighter groups in regard to what would be expected based on his groups at 100 yards then he would be neither ignorant or a liar to say that "my gun groups better 300 yards than it does at 100".
Thoughts???