Can air slow a bullet down enough to the point where it can be non-lethal? We already know that the principal forces acting on a fired bullet are gravity, wind, and drag—the last of which is caused by air. Depending on who you ask, the importance of these variables can change, and some believe that air resistance is actually quite negligible. Of course, the mathematical models behind this are quite complex and in many cases, even deemed unreliable beyond 500 meters.
So here is a relatively unscientific—but interesting—experiment on bullet drag by Matt of DemolitionRanch. Using old flak armor as well as a more modern version, Matt tests to see if rounds that would ordinarily go through the armor can be stopped due to air resistance.