There should be no problem loading the 255 gr. bullet if loaded with the proper powder charge. Some pistols, especially the 1911 type, might have a problem feeding that type of bullet without jamming. The only way to know is to try it and see how well your .45 ACP likes the combination, some pistols will like it others will not be happy with it. It should be interesting, let us know haw your 45 likes it.