Hey Steve, Go here and check out this ballistic chart. I shows the expansion of different bullets at various velocities. As the chart shows the Nosler BT blew it nuts all the way from 3100fps down to 1400fps. Pretty much a POS as a hunting bullets goes.
http://stevespages.com/jpg/bestbullet.jpg
If this link doesn't work just copy and paste it to your address bar.