Has your reloading of the 45ACP been confounded in any way by stray 45GAP brass that has sneaked into your brass collection?
So far, I've found it easy to distinguish between 45GAP and 45ACP brass as it lays on the range floor. This is because the GAP case is visibly shorter and it registers to me as being more like a 9mm Luger than a 45ACP.
Also, do you know whether the GAP takes a small primer or a large primer?