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What you don't know about the WA M4 Gas Magazine
If the magazine is important for an AEG, it's all the more necessary for a GBB!
Remove these four pins. Ignore the one circled in red.
Push the feeding channel a bit forward, and then slide down.
The top part is held in place by two pins.
Removal of the top part is very easy with this clever method utilizing recoil.
Main valve removal should be done with a proper tool only.
Eat your heart out, high flow valve! Even the standard valve of the WA has huge flow!
The inlet valve is disassembled differently compared to normal ones. This one is a bit tricky to do, but the principle is simple.
The magazine disassembled. Not as complicated as you'd first think. A possible leaky O-ring highlighted in red.
The valve lock goes back like this, in case it jumped out when you disassembled the top. It is advisable to keep it down when reassembling, and also when charging gas.
The ingenious NLS feature explained. The amount of liquid in the gas is controlled, and the main valve is in a separate expansion chamber with a siphon tube.
You can always tighten the fit with PFTE tape aka. "Plumber's Tape".

Proper maintenance makes a big difference to performance!

The long awaited WA M4A1 CQB-R and WA M4A1 Carbine were released not that long ago, but they have already taken a good amount of wind under their wings. (Please see our review.) Despite the lack of spare magazines at that time, the first batches sold out in a record time. The magazines turned out to be a slight bit more expensive than we had hoped for, but there are some really neat features in them that warrant an article of their own.


As with any gas gun magazine, the magazines for the WA M4A1 series need proper maintenance and lubrication to keep them working at the best performance. Compared to the common pistol magazines, there are a few things we want to clarify about this new weapon type.

First of all, the high power and heavy moving parts with tremendous recoil means, that the weapon needs some "Oomph" from the power source to be able to provide all that. A lot of users outside of Japan will charge Green Gas (propane) into the gas reservoir. Even with normal gas pistols, Green Gas adds its own requirements to the maintenance. These effects are amplified with the WA M4A1, because the gas consumption is higher.


As Green Gas is released from the magazine when the WA M4A1 is fired, the dropping pressure allows the liquid green gas to "boil" and turn into gaseous form. The gas flow is so hard, that it effectively blows the plunger O-ring of the main valve dry after some time. For this reason it is necessary to keep the valve lubricated to keep the O-ring in good order. Normally you can add silicone oil directly from the gas output hole at the top of the magazine, while the magazine is emptied of any gas and the valve is locked open.

One good trick we found is to push and hold the valve lock down as you fill the magazine, to let the plunger seat better. After the gas pressure is affecting the valve, you can let go of the valve lock.


A more thorough maintenance can be done by disassembling the magazine. Before disassembly, it is absolutely mandatory to make sure that there is no gas in the magazine. After that, it's time to attack the pins with a small punch and hammer. Tap lightly! Only three of the pins at the front of the magazine need to be removed. You can leave the bottom pin in place, but remove the larger bottom pin at the same time. This means you won't get the spring and follower in your face.


The BB feed channel and base plate can be removed by gently pushing the top of the feed channel forward, and then down. At this point you can also remove the bottom plug of the gas reservoir. Tapping the main magazine body with a plastic hammer helps to pull it out by recoil force. Next we remove the top section of the magazine, which is held in place by two pins. It can also be removed most easily by the ingenious use of recoil. Please note that the valve lock can jump out, so operate in a clear plastic bag (or prepare to hit the floor looking for a small spring.

The most common problems in these areas can be remedied by taking care of the O-rings periodically. As with GBB pistol magazines, you can always tighten the fit with PFTE tape aka. "Plumber's Tape". It is wrapped into the groove to make the fit more tight, and silicone lubricant is then added as usual.

Both the gas inlet valve and the main valve should be removed with a proper tool to avoid damage. The main valve is bigger than normal, so some tools may need to have the cavity deepened. The gas inlet valve can be disassembled further by turning the brass inner tube clockwise. The injection tube will come out from the side normally facing out of the magazine, so it's a bit different than normal inlet valves.

The magazine is now disassembled for any maintenance you should need to perform. Looking at the parts separately, you can see that the magazine is not actually more complicated in terms of keeping the gas inside, compared to a regular GBB pistol magazine. The gas reservoir is a single-piece tube blocked from both ends by separate parts, and of course there are the mandatory inlet and main valves.


One of Western Arms' unique features has been the ability to fire a gas gun upside down without getting liquid into the main valve. The name of this feature is often mistaken as "R-Type", but the correct term is NLS, for Non-Liquid Siphon/System. It is not implemented in all pistols because of the volume limitation, but in an M4A1 magazine there's room to spare.

As you charge the magazine with gas, the long inlet valve controls the ratio between liquid/gaseous propellant in the magazine. This is necessary in all gas operated guns, because the BB is shot by the pressure of the gas, not the expansion rate of liquid into gas. After charging the magazine, the level of the liquid gas does not reach the intake tube, so you won't get liquid into the main valve no matter which way around you turn the magazine. This applies to any silicone as well as liquid gas, so adding silicone into the magazine with the propellant is not sufficient to keep the main valve lubricated.