The fuss surrounding that evil nasty stuff called lead is most likely the reason , although it may not be mentioned . Possibly being seen to avoid unnecessary legislation or intervention . There has been lots of talk about lead shot being banned so . . . They have been around for years but recently much more tins seen . Most I see are from Germany , very healthy but different culture of club shooting there - no hunting allowed , with all ages especially young shooters encouraged . It does make sense to minimise lead handling for regular users in this scenario . Cannot see how copper can harm steel , but am no metallurgist .
Time for bed soon so must brush my teeth - have some toothpaste I found leftover in the spare cabinet from 20 odd years ago - in lead tube