Pretty darn close.
Some of you will recall that I had a black charging handle that I wanted to make gray to match the A1 upper for my retro build. I tried buffing the handle with steel wool, which worked pretty well at first, but as I worked the handle, the wear from my fingers polished the front of the handle back to the original black color.
Just as an experiment, I decided to grab a can of Rustoleum Dark Gray Primer and hit the charging handle with that. Since it's cold here, I warmed up the can with my wife's hairdryer while I warmed the charging handle in the oven set on 200.
Pulled it out, cleaned it with acetone and wrapped the forward end of it in a paper towel, and wrapped the rest of the paper towel around my hand so I wouldn't get sprayed. Took the whole mess outside and hit it with a fairly heavy coat, which dried quickly because of the heat of the part. Brought it back in, and once it was dry to the touch, put it back in the oven for another 20 minutes or so just to make sure it was baked on fairly good.
Pulled it out, let it cool and put it back in my rifle.
It's not an exact match, but I think it is certainly good enough and wouldn't be the first thing anyone would notice upon examination of the rifle. The black handle stuck out like a sore thumb, but this blends very well.
Pics:
The pics actually make it more obvious than it is in real life. Best part is, it was under $5 and I can touch it up in about 10 minutes if necessary.