I’ve shot a lot of groups like this with a lot of BB guns and none of them are very accurate past 10 yards. The 400E is actually considerably better than most. The thing to do with them is to shoot them offhand at 10 yards or less. I only benchrest or shoot them from a tripod to demonstrate that there is no human error involved.
I’m still really curious about what a Daisy 499B is capable of, but it’s one of those things where I just want to satisfy my curiosity and see just how accurate BB’s can be. Once I’ve done that I can’t see myself shooting a 220 fps muzzleloading BB gun much when I’ve got guns like the R7 that will shoot tiny groups at 30 yards.