Steve
We've (the LRH member's) had several discussions about this in the past.
I guess the fastest way to get an idea is to look at the reloading manuals from different bullet manufacturers. They often list an effective velocity for the bullet, both high and low end.
My experience has been that once a bullet drops below a certain velocity it ceases to expand on less dense material. As an example, I've shot cleanly through deer with 70 grain Nosler Ballistic Tips (the varmint version BT), the distance was over 500 yards. These were double lung shots on does.
This lack of expansion is not a failure of the bullet but rather from using the bullet outside it's design parameters.
PERSONALLY, I now prefer to use the longest bullet I can shoot. My reasoning is two-fold, the BC is generally higher and I feel that the bullet will begin to overturn earlier in the animal and even if it dosen't expand it'll make an acceptable wound cavity. This is my personal opinion and not based on scientific data but by observations on animals I've shot.
Warren is the terminal effects scientific guru here and maybe he'll point us to more info on scientific data if he's around.
There are many of us here that use bullets and techniques that have proven successful over the longhaul. Like others, I sometimes don't know the exact reason these bullets and techniques work but experience shows that they do and it's hard to improve on success.
