100 Yard Target/Plink- 13 grains Unique or 21 grains 2400 and any 300-400 grain plain based bullet. I shoot hundreds of these every year out of Contender, Rolling block and Sharps 74, cheap, accurate and just plain fun to shoot. Look at the Lyman cast bullet manual for lots of really good loads.
If you believe that smokeless powder is just a passing fad, have a ball with any 400-500 grain bullet on top of a case full of black powder or black powder substitute, very fun and likely to get everyone at the range interested in what you are doing!
regards,
graycg