Did you try a light coat of lube on those Barnes sabots? It might be worth a try.....I took my T/C Pro Hunter FX to the range to sight-in last week. My Barnes Expander sabots WOULD NOT GO DOWN THAT MUZZLE no matter what. I had to pound two out.
I went back to the old reliable 295gr Powerbelts. On top of 100gr of Blackhorn 209, I can shoot 3" groups at 100Y. This is, well, good enough.
So I'm using 'em. This will be my first season ever hunting deer with a muzzleloader. I know the Powerbelts are out of favor now but for many years they killed many, many deer.
I plan to go for the high shoulder shot. I want DRT or minimal tracking.