Looking good. Motivation to finish my M4.
I really suggest against Sharpies. If it's worked for you, fine. But they turn out to be really dark blue, not really black and it can show up under the right light. Also I found out the hard way that Dullcote dissolves the ink, and it bleeds all over the place.
Speaking of Rustoleum, I like the stuff too and use it on the bottoms of my ships. But recently I bought a can of their classic red primer, and after using maybe a quarter of it, it just stopped working. It's not the tip, that is nice and clean. Something in the can to do with the valve, just froze. I've tried about everything, including yes poking a skewer down the tube, to no effect.
$ 8.99 pain in the hiney.
So I went online and since I believe everything I read on the internet, this does seem to be a problem.
Shootski!