All primers have a steel anvil so a magnet will pick them all up. The best way to check is to scratch them with your pocket knife or better yet just take one apart & check all 3 pieces with your magnet then you will know for certain. Ross Puls
A qualifier to Halfmile's post. All shotshell primers have some steel in them.
Nobel Sports, Cheddites and some others are all steel. WW209, Rem209 and Fed209 are all steel except the cap which is brass.