Roadrunner,
The reason accuracy degrades in most bullets as they pass through transonic is that in general, most bullets are overspinning at that point in their flight. If the axial drag and the horizontal drag of a bullet is balanced from the muzzle then this overspinning (sometimes erroneously called overstabilized) does not occur. When a bullet is spinning faster than necessary to keep it pointed nose forward it starts to precess and yaw. The nose is a little high and to the right(for right hand twists) and is drawing little circles in the air. The greater the spin over what is necessary the greater the precession and yaw. Most bullets have axial drag numbers that are much less than their horizontal drag and, therefore, the spin rate relative to what is necessary is always increasing. This means that when they get some 1000+ yds. downrange and are approaching transonic their precession and yaw is much pronounced. During transonic passage the shock waves are collapsing directly around the bullet. When a bullet is overspinning, has pronounced precession and yaw, and enters transonic the collapsing shock waves exacerbates the condition leading to much greater inaccuracies and even total destabilization. If a bullet's flight, and drag numbers are balanced, the Balanced Flight Theory, it will be pointing directly into the oncoming air and can passage the transonic region quite accurately.
On a slightly different subject, energy is not a good quantifier of lethality. Any comparison of energy completely ignores the expansion and penetration characteristics of the bullet. It is the hole that the bullet leaves that causes death. The width, depth, and speed of penetration are the characteristics to measure to determine lethality. There are threshold velocities at which point a particular bullet begins to expand and penetrate differently than it would at higher velocities. These need to be known. For all intents and purposes bullet impacts at velocities below 1500 fps. need to be considered as one to one and a half caliber hole punchers as there is little or no wave effect coming from the penetrating bullet that will damage tissue. At this point energy is meaningless. Momentum and diameter of the bullet are the determiners, and of course, the all important, shot placement.
Energy, or more properly kinetic energy, is 1/2 mass times velocity squared. Momentum is mass times velocity. As you can see velocity is much less important in momentum and the importance of mass, or weight, is much greater. From this and the above discussion it is easy to see that on long shots where the bullet may be impacting at less than 1500 fps. a heavier bullet will have a greater lethality potential at that point than a lighter bullet traveling faster.
[ 07-20-2001: Message edited by: Warren Jensen ]
[ 07-20-2001: Message edited by: Warren Jensen ]