nate45, here's an out of context comment in regards to bullets tumbling. An example could be that as the bullet impacts, it deforms and mushrooms. Now it acts just like an 18 wheeller with front brakes only on wet streets. The back end wants to pass the front end and starts swapping ends or tumble. The BT bullets will shed the core quicker as there is not much a manufacturer can do to get the core to bond to a cone (the boat tail) that has forces on it that are trying to eject the core. Here's the commentary:
In the 1960s we all thought bullet tumbling on impact was a unique and wonderful effect of 1:14 rifling and there was much controversy when the Army adopted the "inferior" 1:12 rifling.
Since that time Army medical research in 1988, confirmed by later ballistic research, has confirmed that (1) all bullets longer then their diameter will tumble in animal tissue, (2) tumbling bullets cause only small additional wounds, much like hollow points, and (3) the massive wounds caused by M193 and M855 Ball are caused by bullet fragmentation tearing the walls of the temporary cavity resulting in 150mm wounds. Temporary cavity requires rifle velocity target strikes (pistol bullets have very minor temporary cavities if at all) and the fragmentation of these rounds does not occur below 2500fps, or about 150 meters.
Hope this has value for you.