9MM, pretty sure on slo-mo the projectile makes a 45 degree left turn and proceeds into the trees @ about a 10:00 angle.
Looks like the max-damage pendulum can swing to the side of either projectile diameter or high-velocity. Hard to determine much else without also knowing projectile construction.
It would be interesting to know if there's a difference between "stem to stern" or mid-ship/sideway shots.