User blog comment:ChishioKunrin/My view on Dust (so far)/@comment-24620600-20140307092353/@comment-24620600-20140307135109

Perhaps it's possible that a crystal influences everyone in a small area around it (so Torchwick hadn't to hold it in his hands) and that this effect is really volatile (that's why Torchwicks shoot turned from red to white right after throwing away the crystal).

However this doesn't seem very likely, because the Dust Shop Owner was surrounded by crystals. If he would be effected by the them, he could have beaten up the henchmen in an instant.

Or, to keep it simple, Torchwick just swichted to another, weaker type of ammo, to cause a smaller explosion in order to prevent the destruction of the entire roof/building.