Please forgive my ignorance. But what does adjusting your primer have to do with headspace?? I am not even sure how the term "headspace" would even apply to a muzzle loader??
Please explain to the ignorant?? For I do not understand??
I can understand that it is a good idea to adjust your nipple so that the primer fits properly?? But I would assume that should be a factory fit?? Not an aftermarket fit?? Shouldn't the primer fit from the factory?? Before I shimmed a factory rifle I would send it back to the factory and have it fixed properly. It sounds like you are applying a band-aid to a problem that needs stitches.
Sorry but I am trying to figure out how the answers address headspace?? Tom.