There are already ICly available ways to train shooting in ways which aren't harmful to your characters.
Someone asked about rubber knives a while back too. Not going to happen.
And there are already nonlethal crowd-control things IC. And the thing I'm thinking of is way more themely than beanbags. Beanbag rounds for the shotguns aren't themely AT ALL.
I don't get why it's OK to spar hand-to-hand, during which people routinely get beaten unconscious and into critical condition, but somehow it's not OK for guns. So comparing this situation to HardBeef and ShootBang is a totally false comparison.
I know, I know what someone's going to say. "What about the wooden bokken. Why do longbladers get a nerfy option." The point of the bokken is neither sub-lethality nor nerf.
If you're hungry for less-than-mortal engagement with your guns, your character probably isn't REALLY using them for their intended purpose in the first place, and probably doesn't even plan to or expect to. Just get out there and shoot stuff. Conflict and danger ARE the game.
Also, some attention is being given to one of the better non-lethal options. A thing which exists but has been unavailable for a while. If we can fix it, it will satisfy the desire here.