I was digging around in some of my stuff and discovered these caps. They were bought when I had my first muzzleloader. Probably in the early 70s.
I still have that too.
Ah yes I shot hundreds of them in the mid 70s. Powerful and corrosive as all heck. Often would almost weld to the nipples and need pliers to remove.Good times. Now I know better how to clean for corrosion.My own caps are as corrosive.No problems anymore .
They look similar to the CVA caps that came in a blue plastic container. They both likely came from the same manufacturer. I still have some from the 70s. They seem to work although occasionally I get a weak one.