If the tube can't be dipped, try hitting it with some Brownell's dura coat bake on paint. Just but a spray can of the base color of the camo dip, that way it will be at least similar in color to the camo and won't stick out like a sore toe. Also, the finish, if done correctly, is VERY thin and VERY durable and even has a lubricating property so the gun should cycle that much smoother.