Big Lube bullets wouldn't have made 'squat' at the Little Big Horn. Custer and his crew met their demise due to poor planning and communication, Custer's zeal for glory, and most of all overwhelming numbers, ie Army vs Indians. I don't believe that it would have had made a difference either if all the Troopers had been armed with '73 Winchesters vs their Springfields, just probably delayed the inevitable. If a person studies and reads the 'true' and most reliable information about the battle and doesn't rely on what a lot of what has been written by those without accurate information and how movies and TV portray it, it can be seen what a military blunder it was. 'Moosemilk' filled bottles and swabs would have been useless too.
Now back to how this thread started, from what I've learned over the years using FF rather than FFF Black causes a little slower burn, thus not allowing as fast a pressure spike when the charge is ignited by cap or primer. Some time ago I went to using FF in my 44 Colt and 45 Colt loads vs using FFF at recommendation of some of the shooters here on CAS that had been loading metallic cases longer than I with black powder. I don't chorno my loads so can't tell you any velocity differences, but they seem a little less in the recoil department and are just as accurate. Supposed to be a little more TLC to the firearm also as I was told. The FF black has worked fine for me in the cartridge department of shooting.