Weather was perfect today so I took a long lunch and re-sprayed the mags like the one shown above.
This time the process was:
scuff duracoat with 220 grit.
dunk in denatured alcohol
2tbsp Magpul FDE
1/4 tsp matte black
1/2 tsp flattener
1/2 tsp hardener
sprayed a single coat over the existing base layer.
Left them to "bake" in the back of my truck all afternoon with the camper shell closed and the truck parked out in the sun.
The color seems perfect. Before the paint was a little lighter than magpul parts when in bright light and seemed much lighter in darker settings. Now it looks like a perfect match. Upping the amount of flattener also makes a big difference.
This is taken in identical conditions to the pictures above. Same position, same room, same floursecent shop light to the right, same camera, same flash setting. The paint is much closer to the magpul plastic.
Here's the same shot with the flash turned off. It's grainy because of the low light but you can see how it still looks the same as the magpul plastic.
These two were taken about half and hour after painting and show the mags in full sun and shadow.