To search for answers about how blood droplets from a gunshot wound can reverse direction while in flight, researchers explored the influence of propellant gases on blood backspatter. They report using numeric modeling to capture the behavior of gun muzzle gases and predict the reversal of blood droplet flight, which was captured experimentally. Their experiments also show the breakup of blood droplets, a future extension of their modeling efforts.
— Read on www.sciencedaily.com/releases/2021/04/210420121533.htm

and

https://www.sciencemag.org/news/2021/04/who-pulled-trigger-gun-muzzle-exhaust-may-complicate-analysis-crime-scenes