400yds would be a true test for .22lr shooters. 5" at 400yds is a touch more than MOA. Sounds plausible enough in theory. I doubt (internet bravado...I know I can't!!!) I could consistently hit at that range, but I shoot in pits open to the winds. Maybe finding a huge, wind-free hangar to try it in to start, get good there, and then try to account for winds.
The winds themselves won't be consistent for the length of time it takes the bullet to travel those 400yds...a lot can happen to the bullet in that time. In the stickied ballistic charts, nothing is worked out to 400yds, but you can see how much deflection by 200yds in 10mph crosswind.
Again not impossible, but certainly very challenging. If I could manage to do it consistently, I certainly wouldn't sell the rifle I was doing it with.