I have not done any kind of spray painting or refinishing.  I recently bought a Sig 551-A1 lower, but the upper is black and the lower is gray.  I contacted a local guy to Cerakote the lower black.  He does good work, but he quoted me $140.  I really don't want to let go of $140 to refinish the lower.  I am thinking about refinishing the lower simply using Krylon; however, I don't want it to look like crap.  I've looked into applying Duracoat myself, but I have none of the tools (compressor, etc.).

140.00 for just the lower seems pretty high.  PM me and lets talk.

The Shake and Spray kit from Duracoat is only $29.95 and comes with its own air can.  I put 7 light coats on an 870.  Had enough left to put a couple coats on the kids airsoft pistols.  Piece of cake.  Several blacks to choose from.  Six months old with a hundred rounds thru and looks great.  I will be using it again.

Poppy i've done a sig 556 upper with wheeler ceramic coat from midway usa and it matched the factory black sig finish very well.  it actually seemed like a better finish than the sig factory finish.  it comes in a rattle can so it's easy to apply but it does need to be heated after it's applied.  350 degree's for an hour.  

http://www.midwayusa.com/product/455475/wheeler-engineering-cerama-coat-4-oz-aerosol-black

i picked up a 556 from my local fun store that had been traded in.  it had alot of swiss parts on it and i wanted the lower for my sbr.  whoever built the rifle had duracoated the upper in sig gray and i needed it black to match my er lower.  here are a couple of pics of b4 and after.  

notice how the sig gray duracoat on the upper is a darker shade of gray than the lower


here's the after with the cerama coat


if you don't mind baking it for an hour i would highly recommend it over just "kryloning" the lower.  it has held up extremely well and the color match is damn close.  it was funny to see your thread as i've been "kryloning" my sig sbr tonight

here's a pic of it last night after test fitting all the parts