Airsoft guns are sold with a bright orange tip, due to a federal law that requires all import/export of firearm replicas to have an permanent orange tip. Unless you are transferring the airsoft gun ownership to someone else, you do not have to have an orange tip on your airsoft gun.
In addition, I noticed that orange tip really stands out on an airsoft field. Therefore, if you use your airsoft gun for competition purposes, you will want to paint the tip black or some other camouflage colors.
In this article, I will demonstrate the proper technique for painting the tip of an airsoft gun. I will be using the JG M5-S6 for this demonstration. The JG M5-S6 is a perfect candidate for this purpose, because it actually comes with an orange barrel cover (see photo below). So during transportation, I can use the orange cover and have a painted tip for game play.
We are going to use spray paint, because it's easy to handle, no brushes to clean up, and applies even coat. But that requires a little bit of preparation.
You don't want to get paint onto the rest of the gun, so you'll want a way to shield it from paint. I happen to have a large plastic bag that I could use for this purpose. You'll also need the blue masking tape, which is the de facto standard for painting. The blue masking tape comes off easy and leaves no residue.
In the photo below, I've made a hole through the plastic bag and used blue masking tape to secure the plastic bag around the MP5 airsoft sub-machine gun (SMG).
Spray paint will travel with air, so it will get everywhere. You don't want spray paint to contaminate your inner barrel. Therefore, roll a bit of the blue masking tape into a ball and stuff into the barrel hole (see photo below). Stuff just a little bit into it, so that you can pull it out easily with a tweezers.
Now, it's time to start painting. You'll need a can of flat primer spray paint (see photo below). They come in flat white or flat black, depending on how bright or dark you want your final paint color. Normally, I just use the flat white. The primer sticks to the surface well and prevents your final paint from coming off.
Give the orange tip a good even coat of the primer. I have used the flat white primer on mine as shown in the photo below. It drys pretty quickly. After about an hour, you can continue onto the next step.
Most airsoft guns are flat black, so you may want to paint your tip that way. However, I only have the semi-gloss black spray paint handy, so I am using that (see photo below). You can also use other colors to camouflage, or to attract attention to, your airsoft gun.
Apply an even coat of the final color to the barrel tip (see photo below). After it drys, you'll have a great looking tip that matches well to your airsoft gun.
Spray paint takes up to 24 hours to dry, so be patient. Find a place where little dust will settle on the gun. It should also be a place where there is little traffic, so that no one will bump into the gun. After the paint fully drys, you are ready to take it to your next airsoft battle.
In this example, the gun happens to have an orange barrel cover. Therefore, transporting the replica firearm with the orange barrel cover should not create tension with authorities. However, your guns may not come with an orange cover.
In that case, you can substitute with a role of fluorescent orange vinyl tape. They are quite inexpensive. Wrap the orange tape onto the barrel for transportation and storage. At a competitive airsoft field, remove the orange tape.