Clays/Claydot and Alliant's relatively new Extra Light are other powders that will produce low pressure loads for vintage guns, whether they're Damascus or fluid steel.
Kirk, I reread the Bell article on long shells in short chambers not too long ago. In most cases, the pressure increase when using a 2 3/4" hull vs a 2 1/2" hull is relatively small, on the order of a few hundred psi. However . . . on some Damascus guns, with very short and sharply tapered forcing cones, you'll find that you need to stick to the short hulls. Appears to be not so much the chamber length, but rather the nature of the forcing cone. Bell also discovered that just lengthening the cone without modifying the chamber usually resulted in some reduction in pressure.
