You are probably going to find the best deal and "safest" barrels by going to a vender such as "Track of the Wolf" or "Dixie Gun Works". They are plenty of others out there not pitching for anyone. They can sell you the stock and custom barrels. Green Mountain Barrels are used on a lot of custom built muzzle loaders. Any quality barrel built by a reputable mfg will be safe within industry standards. If you still have questions or are unsure about what you might have, go to a competent gunsmith you trust, and get their input.