I bought some of these a while back. Great for the wow factor at night, the young ones were ecstatic! I would never shoot it out of a gun I really care about or an auto, this stuff is DIRTY. 2 rounds of it dirties up the gun as bad as at least a half case of regular shells.
Also a side note, do NOT put the shotgun in your vehicle for a while afterwards (or bring it inside)! The residue stinks very much badly!
Shot one off once many years ago, in a single barrel, in a place covered in snow... the only time when there is almost zero risk of fire... I have also set off 4lbs of tannerite, and hope in the near future to set off 50lbs of tannerite...