I replaced the trigger on my MKII with the Clark Custom trigger. I didn't replace the sear, springs, hammer etc. I have had the MKII for 27 years and had not been bothered by the trigger pull or over/pre travel. Mine would occasionally not release the hammer on the first shot of a fresh magazine. The trigger would depress all the way with no results. It would then work fine on subsequent pulls. I removed the trigger assembly, polished the rough edges of the disconnector on the side that rubs against the inside of the frame. That helped but I figured the factory trigger had some side play in it and when I went to pull it, I was putting side pressure and possible pinching the disconnector between the upper part of the trigger and the frame. The Clark trigger required some filing to fit but has resolved that problem. It also has less pre-travel than the original. It seems a little crisper too but that may be due to the polishing of the disconnector and hammer bushing. It was only about $15 from Midway and not difficult to fit but definitely needs filing. I'm not sure if it will work on a MKIII but is worth looking into. While searching for resolutions, I found several web pages where people did various trigger work. Some drilled and tapped the trigger and installed their own over travel screws and even pre travel adjustment screw. I would recommend the "blast shield" made from a piece of aluminum can that covers the trigger mechanism and keeps the grime out.