I had the Cabelas carbine with the same fast twist, same short barrel I think 22" though.
I used T7 and tried 3 different maxi type bullets, The 2 REAL sizes and a T/C Maxi.
I worked those bullets in 5grn increments from 70-100, (5 shot groups) then tried the same with an Ox-yoke overpowder wad, again in 5grn incs 70-100. I couldn't get anything better than pie-plate groups at 50 yards with that thing !

I finally brought it back to the store for "in store" credit and got other gear. I wish I could give ya some better news but that gun just didn't work for me. I did think that it may have worked better with the newer type projectiles, but didn't want to spend MORE money trying to experiment with those.
I really think loose powder is key because you have more options available for the charge, but maybe the fellers on the modern board can give you a few tips with their style of bullet