First, painted the gun one solid color (OD), then using the tan paint I used the the cut out stencils and placed them as close to completely flat on the surface as humanly possible and gave a very quick and light spray. Waited a few seconds for the paint to get tacky and if it needed, gave it another quick spray then carefully lifted off the stencil. Then moved to an area as far away from that as I could so it would dry.
After about an hour of letting everything dry (the paint I use says 15 minutes, but its better to be safe than sorry) I want and using masking tape, covered everything that I didn't want to be touched. Which was like 90% of the gun. Making sure to keep everything at square angles, I cut out areas carefully with an exacto knife. When I was ready I painted the entire gun in dark brown. Let dry for half an hour and very carefully took the tape off.
Took about ten hours to do, 6 hours of which was masking the gun.