My guess is there was a lamination in the bullet, making, in effect, a two-part projectile. The front went flying and the rear piece stayed put.
During the swaging process, two pieces of lead got into the swaging cavity instead of just one piece of lead. This would have left an unglued boundary between the two pieces. One flew off. The other stayed in the case.
That long point puzzles me. Maybe the two pieces of lead were partially connected and when one flew off it stretched the piece that stayed put.

Just my imagination.