That, and the ever present danger of shooting your eyes out!
I used to have a wimpy air pistol. Great for an apartment, it was pretty weak.
Danged if a bb didn't bounce off a piece of corrugated cardboard and come right back and hit me in the face.
Even though it was more of a pain and slower, I stuck to loading darts for a while after that. They stuck in the cardboard.
If this is not just a sarcastic note, no one with any sense shoots withour safety glasses these days. In my Rifle & Pistol club, no one goes on the range without glasses. An autoloading rifle or handgun can pop a hot brass case right back toward your eye. You start training your youth shooter to put the glasses on before loading the gun.