Watching the news, there’s video of the Invading Immigrant Mob where a wall of Mexican Police are on one side of a barrier of bars, and the Mob is on the other side of the barrier tossing rocks, chunks of trees, and anything loose at the Police.
Now the Police can not shoot back. It isn’t (yet) lethal force. It is only physically damaging force. ( A couple of guys tossed what looked like a 15 foot long pipe, or maybe small tree trunk over the top of the barrier…) Now the Police have tear gas, but that depends on the winds and is non-discriminatory as to target. They have tasers, MAYBE, but those don’t work well throug a fence. What to do? Rubber bullets?
What you want is something to incapacitate individual persons, but not kill them.
So what about an analog of the “rubber bullet”. An anesthetic in a gelatin bullet that will go through a shirt and skin, but is unlikely to kill if shot at the legs or torso (not enough energy). So you shoot the folks and they have about 4 minutes until sleepy time. It might take a ‘shot capsule’ approach where each pellet is the size of a grain of sand (so can’t go deeply into tissues).
So the folks assaulting would see shots being fired, then see folks “going down”, so would be highly motivate to back off. Yet nobody would be seriously hurt. (Assuming the police can avoid aiming at heads, throats, crotches, etc.) Just torso or thigh level on down.
I’m pretty sure this can be done, and loads for revolver and shotgun can be made. Semi-auto might need hand cycling, but that isn’t hard to train.
I put this idea in the Public Domain for anyone to turn into products.