This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
I would rather not advocate violence, but I often think they need to be forced to walk over a pit of coals after we give them a lecture on boundary layers and why they don't need to worry so much just so long as they don't stop worrying a little.
A decent 'sport' crossbow bolt costs about £2, a bullet about 50p. The bolt could still work out cheaper if you could re-use it, but in practice it would probably bend.
A .22 cartridge is only about 50p for the better grades. As the range is that preferred by police gunmen, whoops, sorry, "marksmen", i.e. about 12", neither bullet nor bolt accuracy is likely to be an issue.
An alternative is the Idi Amin method:- line them up and give No 2 a sledgehammer....