I've heard over and over that jacketed bullets should not be used in guns that originally were loaded with black powder, ie. 25-20SS, 28-30-120, etc. What do you think about this? Copper is softer than any steel barrels regardless of age, so why would a jacketed bullet wear out an older barrel any faster than a cast bullet? I realize copper is harder than lead, but question it wearing out a barrel prematurely. Also, can you use a spitzer swaging die to make a satisfactory flat point bullet by simply reducing the size/weight of the core so it doesn't completely fill out the point?