"The bit with the poem would be fairly large anyway," Sirius points out as he glance down at the size Kieren is approximating with his hands. He won't be able to guarantee the exact sizes of the pieces that might crumble away, but having spent many, many years blasting things to pieces, he has a fairly good idea of how far back he'll need to stand, at least.

Giving Kieren a light nudge, he pushes up to his feet then and pulls his wand from the back of his jeans.

"You're sure about this?" he asks as he walks a few feet away, glancing about for prying Muggle eyes. He'll be able to put it back if needs be, but he still wants to be certain. It'll be a rather jarring blast either way.