You would have to take the original model into a mesh editor and cut the chunks out. Color the inside of these like ribs, skin, whatever an reassemble. Import the mesh and name it something like "mummyhit1". Use objaction mover to copy the bones from the original mesh to the modified one. Lock all the pieces to the original chest part as a parent. Gaps will probably show between these as the figure moves so you will want to shoot him as soon as possible. Create your walk path and adjust the recoil as the figure gets hit and his reaction. Go through to the point of impact and unlock the chunks from the parent. There is no physics in poser so you will have to eyeball the rate of drop, arc, etc. and set by hand. You need to set the keyframes from time zero to the end. If you set the beginning and end then add frames in the middle you get weird effects like the parts can start moving backward. If you shift the part much it tends to just put a kink in the motion path. So plan your work and work your plan. One other piece of advice I can give you I heard from Chuck Jones at Fantasy Fair 10. I'm going to say this like a quote because it sounds better. "Whenever the Coyote falls off the cliff and the boulder falls on him I always have a few pebbles fall after the fact. It is essential to the timing that this pause happens. Events in real life don't happen all at once or to the soundtrack. I always throw in things that happen off the beat." Good Luck!