I don't know what they are good for, might scare a defiant suspect or something, but they are definitely spectacular. Our FLD who loves gimmicks showed up at a pistol match and shotgun sidematch with some. They put out a lot of fire. Set a paper target on fire at 25 yards. Of course it was a used target, ragged around the bullet holes and easily lit, but it still surprised me. I don't know what kind of residue they leave in the barrel.