The problem is, once you've shrunk the barrel down past 4 inches, you've compressed the action to a point where there is only just barely enough time to get that big ole .45 round stripped from the magazine and shoved into the chamber. Go pull out a full size 1911 and lock back the slide; look through the ejection port from the top down. Notice how far back the slide is - I bet you can even see the top of the disconnector sticking up from the grip. Now do the same with one of your 3" guns. Notice how far back the slide goes in comparision - just to the back of the magazine. This leaves almost no room for error.