For a "just shootin'" load, you might consider 25.0 - 28.0gr./Alliant 2400/405gr. cast. It should give you 1500 - 1600 f/s. If you use 2400 for anything else, you haven't added another gun powder to your larder in the process. There's also a load consisting of 10.0 - 12.0gr./Unique/350gr. cast. I think velocities are in the 1100 - 1250 f/s range, but not terribly sure. These loads strike me as sufficiently low-pressure to be safe in a trapdoor carbine, but please, PLEASE, PLEASE check these loads against data from a manual or four.
