I was looking something up. it was scary to see
http://www.websitetoolbox.com/tool/post/marylandwhitetail/vpost?id=2922832&trail=15#11

I will go to guess that who ever shot that rifle, loaded the sabot with the short starter, and then forgot to drive that sabot down onto the powder charge. Look where that thing split. Right about were the sabot would sit. The is what it looks like to me.

I agree. Short start for sure.

yup.

make a good shooting stick

Holly cow , Someone forgot to seat a bullet on the powder didn't they . I'm glad nobody was hurt !