You probably know those NERF toy guns with a soft plastic darts? They are harmless, unless forced to go at extremely high velocities.
Recording the experiment where NERF dart flies at the speed of sound. Image credit: TheBackyardScientist (still image from the YouTube video)
The following video illustrates a set of real-life experiments where darts are shot using compressed air. Using such principle activation, the same plastic bits attain velocities comparable to the speed of sound. At this point, mechanical impact becomes highly destructive, despite the initial softness of the base material which is used to make the shell.
This experimentation is fun to watch, but don’t try to repeat this by yourself: