Anybody use 4759 in 45 Colt? A friend of mine is working up loads and there isn't a lot of published data. He says he's getting about 1200 fps with a 225gr. SWC and is looking to work on a 300 grain load.
There was an article in Handloader's Digest 40 years ago about loading round balls in 45s (both ACP and LC) using 4759 and priming charges of Bullseye (a never recommended practice in modern journals!) Apparently that worked but it hardly parallels what your friend is doing. I have no doubt that safe high performance loads are possible with 4759 but there is very little tested data........I'd choose something else and save the special reduced load rifle powder (4759's actual purpose) for its designated use.
About the slowest powder I've seen with data has been H/IMR 4227 and it hasn't impressed me too much with a 270 gr bullet. About 1450 fps out of a 20" rifle barrel.