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Tracer Unit built into Magazine

This simple DIY solution to illuminating tracer BBs works great and uses very few parts, but does require some careful cutting and fitting.

Everything is contained inside a locap magazine – no modifications are made to the gun whatsoever. The magazine can turn the tracer effect on or off at will, so you can fire without revealing your position if you need to.


This is a method of converting an airsoft magazine (“clip” is not the correct term, although it’s what most people would call it) to fire “tracers” from an airsoft gun.

In Airsoft, tracers are glowing BBs that are illuminated by a special device before they leave the gun. These devices are pretty cool, but expensive. With tracers, when you fire the gun in low light the shots will look a little like lasers – you will be able to easily see where you are shooting.

You can look at a YouTube video of an off-the-shelf tracer unit here.

What I made is a poor-man’s do-it-yourself version that is really quite different than the usual tracer equipment (and to be honest, doesn’t work quite as well) but is a heck of a lot cheaper and is in some ways more flexible. If you’re still interested, read on.


Tracer BBs are BBs made from glow-in-the-dark material. When this material is “charged” by exposing it to strong light, it glows.

When the glowing BB is fired from the gun, persistence of vision causes it to appear as a streak of light. This is a cool effect, as well as being actually useful when playing airsoft in low light if you want to see where your shots are landing. It’s also just plain neat. It looks like shooting a laser beam, and when it ricochets off something it’s pretty weird to see.


Tokyo Marui (a popular airsoft manufacturer in Japan) makes a tracer unit that looks like a suppressor (silencer). It’s the number one (and pretty much the only) tracer unit out there. It consists of a battery-powered strobe that flashes a flashbulb when an optointerrupter detects a BB has been fired from the barrel. In this way, tracer BBs are lit very strongly as they leave the barrel of the gun. I have one of these. Like most TM stuff, it works great.

At one point, a manufacturer made the B.I.T.S. – or built-in-tracer-system which was a replacement barrel for an Airsoft gun. It had a clear piece through which BBs were illuminated as they were fired. I don’t know much more about this one, or even whether they ever made it off the drawing table.

More recently, G&P has made a magazine that illuminates the BBs as they are fed into the gun. This magazine is most similar to this project. However, the G&P magazines are on once inserted into the gun – there is no way to turn it off besides switching magazines. This could be a problem if you want to fire a few non-tracer rounds in a situation where you don’t want to reveal your position.


This project of mine most closely resembles that last method. I have not seen any of them, nor do I have details about how they work but I found a simple way to make my own equivalent. It’s not loaded with features but it’s simple and effective, and nearly anybody with a little technical skill should be able to make their own in one evening or afternoon.



When I made the LED Megalight I was experimenting with Luxeon LEDs for the first time. I was very impressed by their brightness. I tested shining it for just a moment on some glow-in-the-dark tracer BBs and was rewarded by a strong glow. I knew right away I could use such LEDs as the basis of a tracer system built into an airsoft magazine – just have the LED on as the BBs pass through the feed mechanism into the gun, and that should be that!

This isn’t a system that illuminates each BB with a single flash as it leaves the muzzle like the Tokyo Marui system. This instead is a high-brightness light that lights up when you press a button. While you are pressing the button (which is on the magazine) BBs pass the light source as you fire and you will as a result fire lit tracers. While the button is not pushed, the tracers will not be lit. You should only press the button WHILE firing tracers – you aren’t supposed to always be holding it down. An advantage to this is that if you don’t want to shoot lit tracers (which reveal your position), you just don’t push down the button.

Please do not use this design to learn anything about electronics and LEDs!
I am misusing and borderline abusing the parts involved – the tradeoff is something extremely simple that just works, and I know what I am doing by putting it together in this way. That means what I’m doing here is not the “proper” way of using batteries and LEDs, and what I have done isn’t meant to be used when substituting other parts. By all means use the design I made, but don’t pick up any habits from it. This is nothing more than a way that WORKS and FITS. It is not correct design!


You will need some basic tools (a dremel will be handy), and the ability to solder to small things is an asset. If you don’t feel comfortable soldering wires to small, fragile pins then you will have trouble with this project.


Like most of my projects, I will provide the details of the concept and construction – but the exact method you use will be up to you, especially if you use a different gun and magazine from what I used. The following worked for me:

  • 1x Locap (standard capacity) magazine. I used one for the M16 and haven’t tried any others.
  • 1x Luxeon III white LED. ( supplies Luxeon LEDs.) OR a UV LED (see updates at the end of this page.)
  • 1x momentary pushbutton switch – the slimmer the better.
  • Batteries for power – I used three CR2032 3V coin cells. They are fairly common and inexpensive.
  • Dremel tool, drill, soldering iron, wire, hot glue, etc.


First, remove the magazine insert from the magazine’s outside shell. There should be some little tabs visible somewhere that, once released, allow you to slide the plastic part inside of the magazine out. Then uncrew the halves and remove the insides carefully.

Make sure the magazine is unloaded! Then open the plastic housing by unscrewing any screws. Careful not to lose any pieces – the retainer clip near the opening is under spring tension, and the magazine contains one big spring (though it should not be under much tension itself).

Survey the insides. You’ll need somewhere to put the batteries and the LED. The LED should be placed as near the opening as possible without interfering with any part of the feed mechanism, including the BB retainer.

The LED will need to shine as directly as possible into the BB feed path, onto the BBs as they sit in the magazine and pass by as they are fed into the gun’s mechanism. To do this, an opening needs to be made in the wall of the BB’s feed area, and the dome of the LED should be seated in the hole. If you do this properly, the BB’s dome will fill the hole you made so that the inside wall remains more or less “smooth” from the BB’s perspective and won’t cause the BBs to misfeed.

Use a pen or scriber to mark spots to cut out. File, drill, and cut as needed to fit the parts in where you decided they should fit. Go slow and take your time. Measure twice, cut once. And remember you can always cut away more – but you can’t undo a cut nearly as easily.

Now cut away enough for your batteries. This should be pretty easy – I don’t know about other magazines but there is enough room on the M16’s to even put the CR2032 batteries flat against the magazine’s insert. Keep in mind that the batteries need to be ACCESSIBLE. You *will* need to change them later, because they won’t last very long. So don’t plan on anything too permanent.

Once you have some space cut away for the LED, solder a generous length of wire to the LED leads. Use wire that is small enough to not interfere with the placement of the LED or otherwise get in the way. The side of the LED with a little hole in a tab of the lead is the side that goes to the (+). The lead on the other end of the LED goes to (-).

Once that is done, connect the wires briefly to power to make sure the LED comes on. If it does not, check your connections.

That’s almost it as far as electrical connections go. The (-) of the LED will go to the (-) of the power, and the button switch will connect the (+) of the LED to the (+) of the power supply. But first we need to put things back together a bit.

Fit the LED with wire leads into the hole you cut for it. You can anchor it in place with some hot glue or super glue, but make sure you don’t get any excess into the BB’s feed areas. Run the wires to the outside of the magazine insert so you can close it up – cut away some material to make room for the wires if you need to, but be careful not to cut away any part of the magazine that’s needed for the BB feeding.

Then close up the magazine, making sure to put the BB retainer back in along with the spring and everything else. I find it easiest to close the magazine halves up around the loose spring – but don’t press together the top part completely yet. So you should have about half of the spring (with the follower on the top) sticking out the BB hole. Now push it down into the magazine gently all the way in. Once it’s all in there, push the top parts of the halves completely together and screw it all together. Connect power briefly to the wires once more while looking down the BB hole to make sure the LED still comes on, and you are ready for the next step.

With some work and maybe a little drilling or cutting, you can make the switch location and housing as fancy as you want. For mine, I’m happy with something simple and functional (which is good, because I kind of made a mess of it). I’m drilled a hole in the magazine’s metal shell and glued the button onto the insert such that when the insert is inside the shell, the hole allows the button to be pushed.

An easy way out: If you desire an easier way to go about it, just run the wires from the LED to the outside of the magazine any way you choose (most magazine shells have a hole in the bottom, which would be a good spot) so you have the insert back in the magazine shell with the wires from the LED hanging out. Then, the batteries and the button switch are connected to those wires on the outside of the magazine. Finally, use some tape to secure the batteries and the button in a convenient spot on the magazine. It’s not pretty, and it’s not self-contained inside the shell of the magazine, but it’s much easier to do and works fine.

There are CR2032 battery holders out there, but you can craft your own or get away with using some tightly-wrapped tape on some stripped and tinned wire ends. Just be careful not to cause a short between the (+) side and the (-) side. Remember – keep in mind that you will need to replace the batteries when they get low, so don’t do anything too permanent.

Tuck the batteries and any extra wire into the hole you made to hold them. Press the button to make sure the LED lights (you should be able to look inside and see whether it even comes on).

Don’t hold the button down all the time or you’ll run out of juice quick. Hold it down when firing and that’s it!

If you find the BBs are not glowing enough, make sure the LED is positioned such that the BBs are getting a good, direct hit of the light when they pass by. Also, try firing in semi-auto which makes the BBs move along slower and therefore get a little more light before they get fired.


Here is a video of the construction results, and demonstration that the BBs are successfully glowing as they leave the magazine.


Unfortunately the footage I took of actual firing wasn’t well captured by my camera, so to see a real Airsoft tracer in action, take a look at the YouTube video I pointed out earlier.


It seems that UV (Ultraviolet) LEDs are very effective at “charging” items that glow-in-the-dark. If you’re making one of these from scratch, it might be worth giving it a shot. I’ll try it myself if I make another magazine.