I emailed Barnes asking what kind of velocity was required for proper expansion on the 200gr ttsx and asked if one needed to hit a shoulder for example at long range to initiate expansion. This is the reply I got: The 200 grain TTSX will open at a min of 1600 fps in water, probably 1400 fps in an animal. Our bullets don ‘t use a force pushing against them to open, they just require fluid to enter the nose cavity, so they don’t care if it hits shoulder or not. I have read 1800fps previously but this is kinda exciting. Just thought I'd share.