RE: Knight Full Plastic Jacket
it all depends on your Bighorn action! If the end of the Bighorn action that meets the 209 primer has a concave end to it that covers the 209 primer, you should be protected unless it' s a heavy storm. That feature also renders much less scope blowback than rifles without it.
Examine your action -- close it with a primer attached & look at the seal. If it doesn' t seal good, buy the plastic conversion.
Make Smoke - Not War.... with those using a different style muzzleloader than you.