RE: Muzzleloader Kits
I'm not sure about linseed oil on the barrell. On the stock you'll want to stain it first and then finish it. I usually hand rub on Tru Oil, but I have seen people using spray urathanes etc.
I'm not sure how to finish bare metal to a white finish, although the lock on my fusil is white and I use beeswax to help keep the rust off, although it does rust from time to time.