The McGowen Remage barrels start at around $370 but you would also need a barrel nut....I dont think that is included but im not sure. You lose some barrel OD going Remage and you will need it threaded for your plug. I would NOT use the Badger plug if you went that route. I would use the ASG 209 plug made to handle smokeless. That is a lot of cash to sink into a barrel and not have it designed to handle the extra pressures. The ASG plug also uses a tungsten bushing and will never need vent liners. It should work great with subs and BH209 as well.
https://mcgowenbarrel.com/remington-pre-fit-barrels/
We also proudly offer the Remington Smokeless Muzzle Loader barrels. These barrels are manufactured using the same high quality barrels you’ll find in our other Remington and Savage pre-fit barrels. We can make them to fit your Remington breech plug or the Savage breech plug in 40 caliber (400/408), 45 caliber (450/458) and 50 caliber (500/510) in a variety of twists and any contour on our website is available for these barrels. Muzzle Loader barrels are available in either Chrome Moly or Stainless Steel for an additional $40 to the base pre-fit prices below. We now require sending in the receiver, bolt, & breech plug for Muzzle Loader barrels, due to the variations in the breech plugs being offered out in the marketplace currently.