Use Krylon Fusion Camouflage Ultraflat Matte Black
Don't use that satin finish stuff. Ultraflat all the way. The one with the camo on it and pictures of guns... Get it from CT.
For best results, do not engage full auto on your spray can. Fire the paint in the shortests bursts of semi you can and keep moving to a new area. Once you have your first coat on, go check what's on TV. Come back 5 minutes later, repeat for a few more coats.
Whatever you do don't hold down the spray nozzle for more than half a second. You risk painting a drip on your gun and that looks completely unrealistic.