Science is awesome. Yes, that is a blanket statement but when one realizes that firearms would not exist without it and that because of it development continues to advance does one truly appreciate it.
Or, one can appreciate it without going all wax nostalgic. Shooting stuff is just plain fun, but it gets even better when one starts shooting things and the results do not go as one would expect. Enter non-newtonian fluids which can act as either a liquid or a solid depending on the force applied to them.
Oobleck (corn starch and water) is one of the easiest non-newtonian fluids to create and its fantastic to watch get shot with various objects. The Backyard Scientist (an awesome channel, especially if one has little kits) proceeds to bombard the substance with high velocity projectiles. While none are firearms, the effect of high-speed kinetics is mesmerizing.
For those interested in higher science, non-newtonian fluids are making a large impact in ballistic armor research. The theory is that one can have fully flexible armor that hardens on impact giving the user full range of motion compared to existing armor systems.
Check out the video below and The Backyard Scientist on YouTube.