What are you guys doing, LOL
Shooting a few okay in nonlethal, but large groups? You know why Doom isn't nonlethal?
Pick a trashbin, a box or something and hit it against a wall near your cover.
One mob will come to check the noise, never all of them. Just KO them one by one with Q if there are too many, then when just a few remain, deal easily with the rest.
Remember that to pull the mob behind your cover you need to be in cover mode (press F by a surface). Otherwise you'll just KO the mob in plain sight where everyone can see them.
And don't try to zap ogres with your "chain lighting". Robots yes, ogres no.
Typhoon can be set to nonlethal. Beware, once you make a choice there is no switching typhoon to lethal or vice versa.