SKS, please remember that the SF guys are painting work guns. The finish that they desire isn't permanent, just something to give them an advantage during the crisis of the moment. Big difference between light Green for Africa and a dull brown for ami pajami land.
Team weapons guys will normally have a few cans of paint in the load out boxes that deploy with the ODA. Once the Team isolates and has a clear idea of the mission weapons and kit will be cammied appropriately.
Cleaning the guns will take some of the finish and they will have to be occasionally touched up. After a few paint jobs the guns are usually stripped down (carb cleaner) and then given a fresh camy job.
Paint the whole rifle in the appropriate light color then place ripped up pieces of newspaper over it and throw some dark paint on it. Again you can always go darker later but it’s a pain to go the other way.
The paint will smoke a little on the barrel but then settle down and be fine.
Watch painting mags as the paint sometimes causes the mag to hang in the well. Paint just the lower portion.
If permanent is what you want then go to
www.shootiniron.com/index.htm. Mac does great work and is dirt-cheap compared to the big names. I've got a 24" bull barrel on a Diamond lower heading his way in a week or so. All around good dude.