The worst primer I ever shot was a Winchester WML 209 not to be confused with the Winchester W209. On the outside of the Winchester WML 209 it claimed they were made for inline muzzleloaders. Those WML209 blew the breech plug retaining spring apart on my Black Diamond. On my Knight Disc, it started to wear out the back of the breech plug where the disc primer carriers rest against the breech plug. So we do not use them anymore.