When I had a baby dragoon I used single 0 buckshot in it almost exclusively. A 5 pound bag, if you can find it, lasts quite a while. They are uniformly round swage in nice, and in my experience, shot really well. Back in the mid 1970's, you could order Remington brand buckshot from Dixie Gun Works. I haven't seen their catalog for a few years now, so I don't know if they still carry bags of buckshot. Another good size is 000 buck--it's .380 diameter and works very well in Navy Colt repros.