Ron…, I’d probably look at moving the barrel back a tad, to utilize the liner, as well. Another option, as I’m sure you know, would be to slightly notch the breech plug. Pros and cons associated with that, as has been discussed many times. A third option would be to cone the barrel on the outside, at the pan. I’ve seen a few original muskets that had this treatment. They weren’t Dublin Castle Bess’s, however, so not sure of the historical accuracy, if that’s a concern. Best,
Ed