more'n likely someone's going to jump in and disagree with broom jockey about the jacketed, but it won't be me.
After playing some with black powder my favorite loads turned out to be 22.5 grains of 4759 under the Lee hollow based bullet cast of 20/1-lead/tin. This load matches the settings on the Buffington sight and holds the black for me and, so far as I know, it matches the government carbine load.
to replicate the government cartridges there's a wonderful book out there here's a link:
Keep in mind that this book is about replicating the original cartridges and is not about cartridges tailored to your specific rifle. The author, Spence Wolfe comes right out and says this repeatedly and he points out that you should expect loads that will achieve 4' of accuracy in any trapdoor that is in good shape. I find the book both entertaining, informative and well worth the money. In advance I'll tell you that there are one or two naysayers out there.
Keep us up to date on your shooting progress!
"A man with a tractor and a chain saw has no excuses, nor does he need any"
Me. "Consistency is the hobgoblin of little minds" Emerson "Consistency is the darling of those that stack wood or cast bullets" Me.