The idea of a gun that fires self-propelled rounds being a common weapon is shockingly realistic. There are plenty of real world examples of guns that meet that description well. Gyrojet guns, recoil less guns, and milkor variants have been proven to fire self-propelled bullets. Some have even been used in small instances in war. Hell, the us army at once banned a proposed bolter-like patent over the weapon’s potential lethality.
Bolt guns are special in the sense that they really aren’t fictional. These weapons are just a look into what weapons could look like in the near future, which only makes me appreciate what we have in the present so much more.