80 grains of BH209 with a 350 gr Hornady FPB can/has/will shoot sub MOA for me out of my Huntsman, with several sub .5 MOA 3 shot groups. It is the most accurate bullet in the Huntsman, but there are several others that are no slouches. 70-80 grains of BH209 with a 440-460 grain all lead conical with a fiber wad can/has/will shoot sub MOA as well as several saboted bullets in the 200-300 gr range sitting on 80-100 gr of BH209. The Huntsman is the least fussy muzzleloader out of all 13 of my muzzleloaders, which include Whites, Knights, and T/C. The ONLY bullets I would say that DON'T shoot very well out of my Huntsman are the PowerBelts, but I wouldn't shoot anything bigger than a coyote with one of those anyway.
Of course none of that is possible with the standard primer carrier breech plug, as it leaks like a sieve, and is not BH209 friendly. Sounds as if you're already over that hurdle?
I would say that the Huntsman (mine) favors the heavier 300 gr saboted bullets over the 200 and 250 grain bullets. So, in my case, I can shoot most any type of bullet I wish to from the Huntsman, and do. Try some 350 gr FPB's or lead conicals if you don't like saboted bullets.
I am no expert, but I have shot a LOT of bullets through my Huntsman and used to participate MUCH more in this forum. If you want some more specifics on loads, I have done several range reports here in the past that you can check out by checking my past posts.
Good luck, and enjoy your new rifle.