Timerover51
SOC-14 5K
In Murray Leinster's Med series, the protagonist, a member of the Med Service found himself needing to fight a bunch of bad guys.
Being a doc he didn't want to kill them, so he mixed up a batch of quick-acting "knockout gas" and loaded it into a battery-powered spray paint gun (the gun sprayed in a very fine mist, and with the nozzle set at narrow it had a range of ~10' and a coverage of ~2' diameter area at that distance).
That one is the "Mutant Weapon", Astounding 1957. Good story by the way.
The problem with non-lethal weapons is that they can come back and kill you later.