I think if you check there are a lot of people that use the bullets with abrasive on them to break in new centerfire barrels. It sort of depends on what you think is required to "break in" a barrel. In the case of the muzzleloader a lot depends on how the rifle loads which is not part of the centerfire routine. My Omega was a bit#@ to load and polishing with JB made the loading a lot easier. All rifle barrels have some machining roughness remaining. Probably the cut ones are a little worse than the button rifled ones but again it is sort of your decision. As I mentioned before just a lot of shooting solid lead bullets will eventually break in your muzzleloader. Doc White says to not be concerned with how your rifle shoots until the first 200 loads. Thats a lot of shooting for me as I have trouble getting that much range time. With four new rifles last year that means 800 rounds.