Comment by nucleardog

Heard similar stories from many people. I have my own--

I was at a range shooting this old revolver with worn seals. Every shot, unburnt (or sometimes burning) powder was flying backward onto my face and arms. I basically took a gunpowder shower.

Got up like 6 hours later and went to the airport to get on a plane. Got swabbed. Came back negative. Got on the plane.

So... yeah, not really sure what the swabs are doing. I have to assume it's more an issue of "they're not intending to detect that" than "failures to detect" because otherwise the repeated misses here are just a little too big to believe.