I wanted to test both bullet and autofracture. This is with Houdini 12.5. Sim time was quite long, a few days. Bullet seems to give strange behaviors when the pieces are too tiny they often go crazy with rotations and sliding, so I used some grouping to delete the ones that flickered too much.
I usually add debris and smoke, but it wasn't part of this exercise, I wanted to see how far the autofracture would go.