Depleted Uranium Frizzen (1970s, 1980s)
In the 1970s, thin sheets of depleted uranium (DU) were sold by someone in Florida as a facing material for the frizzens used in flintlock rifles. The advertisements claimed that the uranium was so effective that it would work well even if struck with "a dull flint or any kind of rock." These claims were not far from the truth - being pyrophoric, the uranium could generate consistent and intense showers of sparks.
While DU provided a reliable method to ignite black powder, the tiny uranium fragmnents that became airborne when the flintlock was discharged posed a potential inhalation hazard. Gun enthusiasts were warned about this problem and told not to face their frizzens with uranium in the August 1992 issue of Muzzle Blasts magazine.