There is no lip cut in the chambers for the ACP case to headspace on, if there was the 454 and 45 Colt would not fit in the chambers. If perchance the chambers were bored straight thru and you had to use clips, moon, 1/2 moon or any other there would not be room between the cylinder and recoil shield to allow the 45 ACP in the cylinder to allow the cylinder to be closed. Confused yet?