At what speed do you believe one needs a bonded core, partitian type or X bullet for a, prepare for the worst double shoulder shot on moose or elk size animals? My best guess would be maybe 2500fps or faster. A shot on a moose I made at 640 yds with a 400gn Swift A-frame (2650fps) 416wby broke one shoulder and exited, indicating not enough expansion for the amount of velocity left. The other notable shot was at 200yds, same bullet, through the neck and scapula and stopped under the skin with .750" min diam. The shear shock must have severed his cord because the spine was missed by an inch and half. He hit the ground sideways and never twitched once.