Since we're talking about blanks now, I can tell you this, back in the 1980's we were training with paintball guns and sometimes blanks in our service handguns. Someone got the idea of loading a cotton ball in the blank cartridges believing that it would shoot out and harmlessly tap someone.
Well, our armorer went to the nearest convenience store and bought a bag of cotton balls. Problem was they were not real cotton, but rather some synthetic material. When fired, that synthetic cotton ball came out like napalm. The flaming material stuck to you!
A couple of holes burned in shirts, and we were done with that.
And paint balls - I was hit in the back of my bare hand by a paint ball. Hurt! Raised up quite a welt.