I have a new Knight Mountaineer .50 "bare primer" rifle that I am pleased with. I haven't developed a hunting load yet, but am pleased with what I have seen so far. I do wish I had purchaed an Ultralight instead. The Mountaineer is kind of heavy and the flat bottom surface of the stock makes carrying it less comfortable that a rounded bottom. But since I anticipate this being principally a tree stand gun, I think it will be fine. I replaced the stock breech plug with a Lehigh breech plug with replaceable vent liners.
As far as inlines and the spirit of primitive seasons, if we only use sidelocks then we have to decide how primitive is primitive. My Pedersoli Hawken Hunter has a 1:24 twist, faster than my Knight, and will shoot sabot rounds as well as, or better, than my Traditions Pursuit XL .50 1:24.