Do the oversized brush thing, then have him turn around and shove it up his butt to remind him that hot-loading anything is stupid and dangerous, not only to himself, but the shooters around him!!!! Seriously though, it the brush doesn't work, I've had success bending a coat hanger just enough so that the end goes into the groove and you can pull it out that way, works on my .243 anyway. I don't recommend doing this with an expensive custom barrel, you could scratch it badly, I do mine on a .243 M788 factory barrel.
Selmer