RE: Peifer muzzleloader Help
Now that's a tall order. I know where a used PeiferRifleis but they are asking $300 for it (rediculous).
What's wrong with your breech plug? Is it the one with the nipple fixed or removeable?
Otherwise, you could go to a machine shop and have them machine you one.
What is the thread diameter and pitch? Perhaps you can McGyver a different plug that would work.