I have several of these with 5 ½” and 7 ½” barrels. The .45 Colt cylinders had small throats and required reaming. The .45 ACP cylinders were also a little tight. I had to open a couple of them, too. One .45 ACP cylinder measures .451”, but shoots so well with mil ball I don’t want to change anything.
In the .45 Colt, you can get some inconsistency due to the large case and small powder charge. The .45 ACP has a smaller case with less excess case capacity, but the bullets have a longer freebore. If the throat is not too tight or too large, the bullet can make the jump from the case to the rifling consistently.
My .45s shoot well with both .45 Colt and .45 ACP cylinders. The S&W 25-2 and 625s also have long freebore and they shoot well, too.