T/C Hawkin or Lyman GPR
Hawkin more expensive, has 1:48 twist shoot's RB pretty well, not so good with Sabot's.
GPR 1:66 more traditional, twist shoot's RB Great, not for shooting Sabot's.
I have owned both and both are great, I sold my Hawkin because
I like a Traditional Rifle better and it feel's better.
Accuracy was identical with both rifle's.
Also mine are 50 Cal. percussion, not a big fan of flint lock, just a personal preferance.
Also try 777 powder it is awsome.
Like was stated before, enjoy what you get the way you get it.
Keep your powder dry.