Non lethal weapons are often a misnomer. Nonetheless, I’d like to give armies the option of scaring their opponents rather than annihilating them.
Today’s invention is a bullet which is actually an explosive shell. This allows it to be fired over a huge variety of distances with high accuracy.
On impact, a percussion cap in the nose fires the internal charge which explodes in the forwards direction through a small array of ports in the nose. The bullet is stopped in its tracks by this retrorocket effect before it can cause serious injury
The target individual would feel this blast and no doubt have his/her uniform charred. Whilst remaining unwounded, this would greatly lower morale and the will to continue fighting.