I assume you know not to shoot jacketed bullets in the old soft steel barrel. Alliant shows a max load of Unique at 7.4 grs with a 180gr lead bullet. I'm shooting 7.0grs Unique outa mine and the 1898 Colt Thumb buster. Accuracy has been from the rifle at less than 2" groups at 50 yds. The Thumb Buster shoots about the same at 25 yds.
By the way, you send me the rifle and I'll send you a nice feather.....that way we both can be tickled pink! And yes, I'm envious!
FWIW, if you need to buy brass, skip the Winchester brass and buy Starline. It's far better brass. The bullets I shoot I get from Missouri Bullet.