I do not know of anyone who has ever shot a 22 this far for groups...however, I do know of several older men at my grandpa's local range who have identical setups, and very good results at 400 yards.
A accurate 22 rifle (I want to say Finnfire, but I know this isn't it)
Bushnell 4200 6-24x (100% on this)
Federal target ammo (712B is also on the tip of my tongue, but again, not 100%)
For fun they sit metal coffee cans at 400 yards next to a gong, and turn their scope to a precise power, somewhere between 16-24x. Instead of using crosshairs they use the very bottom of the scope, when the coffee can is halfway in view, they shoot. IF they miss, they are never more than a couple inches off unless the wind changes. I would say they are getting 10" or less groups while the wind stays steady. I was able to ring an 18" gong all day off hand with this setup, a guy let me try his. Next time I'm at the club I'll try to get more information, maybe a video to explain.