Hi Frank! I built the Meng Mustang last year and it was a real joy. I loved the parts breakdown. They really did a good job because it made it easier to paint because they separated the parts based on what color(s) they were supposed to be.
I, too, ran into the issue of the leading edge gun inserts. However, I found a super easy way around this that worked perfectly. In the review, the author stated:
"Assembly of the wings went smoothly except for the leading-edge insert with the machine gun muzzles. I could not press them properly into place and needed to fill the interior structure. After that, the part was slightly recessed on top and needed filler underneath."
All I did was thin the plastic from the inside of the inserts. Pretend the gun muzzle insert is like the letter "C" when viewed from the side. I used an Xacto knife to carefully carve away some material from the concave side of the insert (the part that will face inside the wing). After a couple of trial fits and a little bit more carving away of the plastic, the insert fit perfectly in place. So we're talking all of five minutes worth of work here.
In all honesty, that was only part of the build where I had to exert any effort. The rest of the kit went together wonderfully.
I am just an average modeler and I would not hesitate to get this kit again.
Eric