That's a great question! Not an amateur one!
When dealing with anything that flies (airplanes, rockets, and bullets) there are two drag forces being place on the object: Induced drag and parasitic drag.
Induced drag is the resistance the object faces when pushing against the atmosphere as it pushes through it.
Parasitic drag is like the turbulence you see in the water behind a boat. It swirls the air back at the projectile and disrupts its flight creating drag. These swirls are one of the reasons airplanes have tips on their wings. It breaks up the swirl and improves lift.
These forces are what must be overcome for successful flight. We have all seen some really cool designs the military and innovators have come up with making objects more aerodynamic.
In the case of a long vld bullet, induced drag is minimal because of the shape of the ogive.
Here is the theory behind the bullet going to sleep:
Between the forces of the propellent exiting the muzzle (the importance of a proper crown), the bullet piercing the atmosphere when leaving the muzzle, and the parasitic drag produced by a long projectile piercing said atmosphere, the bullet is a little unstable from all these forces.
A well made bullet that has a concentric jacket will spin and stabilize itself like a gyroscope once these effects are reduced by distancing itself from the muzzle.
Not to belabor the point of having a concentric jacket, but... the bullet is spinning so fast that as long as the jacket is concentric, the bullet will spin around its center of mass.
In the case of long, heavy vld bullets, this creates a very stable projectile.
The reason you could see issues at 100 yards is because of how fast everything is happening. It could take a quarter of a second for everything above to transpire. If 100 yards comes in a tenth of a second, then you would still see a little stability issues.
Clear as mud?
