Sounds like my experiences with IMR4227 in pistol loads for the .41 and .45 Colt... out of the shorter pistol barrels, it was dirty and not that accurate. It’s quite possible if I ramped up the charge they might have cleaned up, but that was not the load I was looking for, I have H110 for that. Now... IMR4227 (and I suspect 2400) performs admirably in a rifle barrel with those cartridges, and that’s where I use them, and just stick with Unique for the pistols.
I recently bought 2# of 2400, and I’ll give them a test drive in the pistols, but I really don’t expect much.