There are various ways to camouflage your air rifle, in this post I’ll look at a few approaches I’ve taken.
I guess the first questions to ask are, why camouflage my rifle and will it make a difference? The answers are to remove shine of the metal work of your rifle when hunting, and to help blend in which is fairly obvious. The next question though, does it help depends on what you are hunting, the conditions, and how you are using it. If I am in full camo clothing and plan to sit at the base of a tree while squirrel hunting, I think having my gun blend in helps…. a lot. But it’s not just the camo, squirrels for instance are very aware of movement, and having your gun blend in makes small movement blend better and draw less attention from watching eyes. However the best camo in the world won’t help if you’re fidgeting and moving your hands, feet or waving the camo gun about. Other game such as jackrabbits will spot you as soon as you break cover, but don’t take off immediately because they rely on their speed when the need to move hits them, and I haven’t found that camo has changed things much. But once you decide that camouflaging your rifle makes sense, there are various way to approach the task.
There are a couple of options if you want to camouflage your guns for hunting. You can use various camouflage tapes and gun socks, or you can paint it. Both methods have pros and cons; when the gun is camouflage taped you can apply a tape that very closely conforms to the environment and remove it or change it as required. It is fairly cheap and won’t ruin the finish on you gun. On the negative side, it does not have the finished appearance of a painted gun. Painting is also inexpensive and gives a nice appearance to the hunting rifle, if you do it right. However it is permanent and may not be the solution if you hunt a lot of different types of country as I do. One trip I might be in the swamps of the deep south, and the next trip in the Mojave desert. After reading a very informative article on the internet (by a gentleman I’d love to credit but who didn’t give his name) I decided to try my hand on an old Crosman multi-pump I had lying around to see if I could do it. It worked pretty well, but I was not convinced enough to do it on one of my better rifles. I typically go with a modified tape / gun sock approach, as I find it suits my needs better.
To use tape, I start by disassembling the gun. I take a camouflaged shotgun sock patterned to match the territory I’ll be hunting and cut off the sock cover. I pull this portion of the sock up to the grip, and then tape with a matching camouflage tape. I then start applying tape from one side of the action inset to the other, so that when I put the gun back together the action will hold the tape in place. You can then apply tape, wrapping it around the barrel from the muzzle back to the fore stock.
An after market finish gives some latitude in picking the most applicable pattern for the areas you hunt. But it is permenant and can be expensive. 
Painting your own stock is an effective, easy, and cost effective approach. 
There are also several tapes, sheaths and other covers that slip over your gun, that allow several patterns, easy to switch, and cost effective.
I handle the scope a little differently; taking another piece of the gun sock intended for the shotgun barrel I put a split lengthwise down the sock so that it fits over the scope and mounts, then tape it in place with the camouflage tape. The slit can be pulled open to reveal the adjustors when required for fine-tuning the scope.
The beauty of this approach is that it takes only an hour or two, and can be removed in 15 minutes. There are a variety of different camo colors and patterns, so it is easy to change as my hunting venue changes.
If you decide to paint, the paint which holds up best for a gun finish is an enamel. This is the same type of paint used by model builders and other hobbyists. You need to find spray paint with a flat finish in dull brown, olive and green. These colors are ideal for a basic fall camo pattern. You can pick up the supplies for a few dollars at any hardware store or home improvement center.
I’ll often just tape up the most exposed parts of the gun. 
That might only be the barrel. 
Or you can do a hybrid, here I’ve painted the stock on one of my marauders, and used camo tape on the barrel, air reservoir, and scope.
You will also need to obtain a supply of very fine grit sandpaper to remove your guns existing finish. This also ensures that the paint will bond to the surface, which can be a problem if not properly prepared.
Before painting the gun has to be disassembled, degreased and masked off to protect the working parts. Sand off any rust that you find and treat with rustoleum or some other anti-rusting agent. Degrease and clean your rifle with white spirits. After the gun has been cleaned and wiped down, do not touch it with your bare hands. Before painting plug up the muzzle, tape up the trigger housing and all other moving parts. Break the barrel, place a small piece of tissue in the breech area and close the barrel again so the tissue is trapped in-between; this stops paint getting into the air transfer works. Tape off the scope’s lenses and adjusters being very sure that the masked areas have been sealed up tightly.
The first coat is the base coat, and after it dries apply a coat of olive, which is the best base color for camouflage in almost any environment you may hunt. Make sure you have painted the entire gun and scope, and then let it dry. I suspended the gun on a piece of wire from a rafter in my garage so that I could give it a complete coating on all sides. To finish the paint-job spray the darker green paint in a broken pattern, which will blend with the shadow and vegetation in the field. This same technique is applied to the stock, action, and scope. When you are done, leave the gun to dry for the period stated in the paint instructions, and finish off with a good coat or two of varnish.
