Exasperation or wot......... We've got to 3 pages (so far I hasten to add.....) relating to a trivial mechanical fault that STILL ain't cured! I can see what's wrong from here. The left front magazine lip isn't controlling the movement of the nose of the projectile. It REALLY is as simple as that and in truth an everyday minute-on-the- bench repair. You test the car with the fuel it was made to run on. Get rid of the drill rounds you are using and test it with .303" NATO Mk7 ball. Fix it and be done with it!