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Western Arms M4A1 CQB-R
  • Manufacturer 
     Western Arms
  • Model 
     M4A1 CQB-R
  • Capacity 
     50 rds
  • Weight 
     2850 g
  • Power 
     380 fps
  • Power Source 
     HFC134a, Top Gas
  • Blowback 
  • Hop-up 
  • Shooting Mode 
     Semi, Full Automatic
  • Construction 
     Fiber-reinforced polymer and metal


-Tremendous blowback
-Realistic construction and operation
-Very good accuracy and power


-Some light FRP parts
-Cooldown during extended bursts


Overall a very exciting rifle from Western Arms, that answers to the calls of many Airsoft enthousiasts for a realistic gas blowback long arm without the need for an external gas rig. The performance is on par with AEGs so you can actually skirmish with this weapon!



Does the M4A1 really need an introduction? Maybe not, but since some of the readers may have been born when the carbine was adopted, a briefing may be in order. The M4A1 is a self-loading select-fire carbine variant of the M16 rifle, both based on the AR-15 archetype developed by Eugene Stoner in the 50's. Ever since the first M16 was brought into service, the rifle has been updated to improve on the original design. Shorter variants were developed quite early for vehicle crews and special operators, and these carbines have been following a parallel developement line with the full length rifle.

Western Arms is a well known name throughout the Airsoft world. Until recent years they held the undeniable lead with their best-known 1911 and 2011 variants, and even at the time of writing WA is still making the most interesting selection of models, while others stick to the basic 1911A1 pattern for the most part. While the Tokyo Marui Hi-Capa and 1911 hold the leading position of "consumer pistols", those with a taste for the highest level of quality and detailing still opt for Western Arms.

Airsoft gas blowback rifles as an idea are not really new. Those who have been in the sport for a long time will remember the Kokusai Crimebuster as well as the Tanio Koba 10/22. More recently Marushin has released a plethora of 8mm blowback models. As nicely made as the Marushin blowback rifles are, their WWII appearance puts them in a niche market, and the caliber doesn't help breaking into the mainstream either. There are also gas blowback rifles and submachineguns with external gas, such as the Escort MP5. While external rigs are much less restricting than their reputation - and can be hidden in the gear quite nicely - there is still a definite demand for having everything inside the weapon. So let's see what Western Arms have to offer with their self-contained 6mm blowback M4A1 CQB-R!

As realistic as it gets? Full stroke blowback with a realistic bolt carrier that acts as a loading nozzle!
Right side view of the CQB-R, a compact assault rifle.
The weapon is well protected by styrofoam in the cardboard box. The box has room for longer models to come...


The WA M4A1 is a gas operated blowback rifle. The blowback principle is no different from the famous Magna Blowback of WA pistol series, but it is fitted to act as a heart of a larger weapon, so the components are larger and heavier as well. Gas and BBs are contained in the magazine, and the valve lock is also built into the magazine, following the tradition of Western Arms. The lower receiver has a firing mechanism that resembles the real M4A1 firing mechanism very closely, and functions with the exact same principle. The hammer spring is formed differently and it stops pushing the hammer before it physically hits the firing pin. This allows the firing pin to retreat after the hammer has been dry-fired (=decocked) so you can insert the magazine without damaging the firing pin and/or magazine valve.

When the hammer hits the firing pin (in the lower receiver) and forces the valve open, the gas is directed from the magazine into the loading nozzle, and shoots out the BB. The floating valve blocks further gas flow into the barrel, and the gas is directed into the blowback cylinder, forcing the bolt carrier to propel back. After cocking the hammer, the bolt carrier trips the valve lock to close the gas flow, allowing the spring-loaded loading nozzle to retreat and the bolt carrier to spring forward, chambering a new round from the magazine. The rear of the loading nozzle acts as a piston in the blowback phase, and the bore size is quite significant in the WA M4 compared to any pistol. This allows the gun to propel heavy 210 gram bolt carrier with great speed, resulting in a blowback you can really feel against your shoulder!

The all metal outer barrel has a 14 mm right hand (CW) thread in the front, so standard flash hiders and silencers can be readily attached. While most of the sound comes from the racking sound of the bolt carrier, a silencer muffles the pop at the muzzle nicely and can make a difference to how easily you are spotted by players in your firing area. The inner barrel is 53 mm shorter than the 10.5" CQB-R outer barrel. This is partially to limit the velocity to keep the velocity legal in Japan, but also the floating valve would have to be modified to let an increased "dose" of gas into the barrel to keep pressure behind the BB through the internal ballistic phase.

The upper and lower receivers of the WA M4A1 are worthy of special attention. As opposed to popular belief, it is legal to produce airsoft guns with a metal receiver in Japan. Still, the WA M4A1 has polymer upper and lower receivers. The reason for this became very clear when we fired the carbine the first time; the M4 kicks like somebody put something in its drink! A pot metal receiver would be unlikely to stand this kind of abuse (from the inside of the gun) for long, so Western Arms made a smart move and used fiberglass-reinforced polymer as the material. The weight of the receivers is a bit on the light side, but the finishing is a dull black and it doesn't look toyish at all. A durable metal receiver would have shot the price of the WA M4A1 through the roof, so for the moderate price we can't complain. Having said that, we are looking forward for the metal receivers announced by G&P as well as Inokatsu, because metal has the heft and realistic feel that FRP can not provide.

The top of the magazine has the valve and valve lock integrated. You can disable the bolt hold open to shoot without BBs.
The fill valve is located in the rear of the magazine, better protected from elements than the traditional placement at the bottom.
The hop-up adjustment is in the base of the outer barrel. The red arrow points towards more, blue for less hop-up.


The magazine is heavy and feels realistic, being as it's all metal made with a dull gray finish. The fill valve is located in the rear of the magazine, which is odd to anyone who is used to gas pistol magazines. On a second thought this is a good decision, because the bottom of the magazine is subject to dirt when you are in the field. The magazine holds 50 rounds, feeds every one of them and locks the bolt carrier back after the final round. While the magazine shot all the BBs out and locked back reliably when shot in semi and short burst, a continuous burst of 50 rounds cooled down the magazine to the point that the pressure was not sufficient to propel the bolt carrier all the way to lockback. The bolt hold open -feature can be disabled, so you can shoot the weapon without BBs to show off the blowback, or for theatrical purposes. Please see our separate article about the magazine.


The detachable carrying handle is made of a heavy metal alloy, apparently to balance the lack of weight of the FRP receivers. With the carrying handle attached, the WA M4A1 weighs in at a nice 2850 grams. The rear sight is adjustable for range and zeroing the windage. Zeroing the elevation is done with the front sight.

The RIS system has the tightening screw in the front - as opposed to RAS that has the screw in the rear - and it is all metal made. While Hong Kong and Taiwan made CNC-machined railed units are admittedly better in terms of looks and durability, for a die-cast RIS the WA is certainly not bad. The rails measure a hair under 21 mm, and it fit together perfectly with all the accessories we could throw at it.

Aftermarket front sets are available from G&P, and some of them can be fitted with an M203 launcher, to further accessorize the M4A1. You can use M203 models made for the G&P series. These front sets include:

  • WP17
  • WP15
  • WP13

    The pistol grip is also made of a fiber-reinforced polymer, but the finish is different compared to the receiver. This creates a realistic contrast, as you can not immediately tell that they are the same material. The grip is flat, so it has an advantage in realism on its side against AEGs. Out of all of the electric M16 series, only the Systema PTW has real grip dimensions. Western Arms goes even further than just the external dimensions, and the grip can actually be replaced with any grip made for the real M4/M16 series! The metal buffer tube is mil-spec sized, and we've already seen our customers install the real MIAD grip and CTR stock to improve the ergonomics.

    After years of coming behind Tokyo Marui in Hop-Up technology, Western Arms has finally made a major leap in this area. The hop-up features two pressure points for the BB to center it better in the chamber, and it provides a very consistent spin. On top of that, the hop-up is adjustable by a dial that holds the setting well, and provides tactile clicks when you turn it. With the carbine in your hands and the barrel pointing downrange, you can turn the dial without turning the weapon upside down. Adjustment towards the left RIS rail increases hop-up, while the direction of the right rail will decrease it.

    The internals are very similar to the firing mechanism of the real thing, and the various parts have the exact same functions. The trigger pull is a realistic single-stage type with no slack, and the safety can not be engaged when the hammer is down. Most of the internal parts are made of a die-cast metal alloy. While this works with pistols and anyone who uses HFC134a, green gas (or propane) is the preferred propellant in most parts of the world outside of Japan. The greater pressure as well as the heavy moving parts mean that it may be necessary to reinforce some of the internal parts. G&P has already released valve locks and parts for the firing mechanism, and we are looking to see more of these reinforcement parts soon. For some reason Western Arms decided to make the flash hider and front sight out of FRP, but this can be quickly fixed with parts from G&P.

    The grip and lower receiver are in fact both made of FRP, but the finish is different for a realistic look. Real grips are interchangeable!
    We've seen a working forward assist with a function before, but this one serves to actually push the bolt carrier forward!
    The functional bolt hold open has a steel reinforcement embedded. This part worked itself loose after 1000 rounds and was found in the firing mechanism.


    When it comes to gas blowback weapons, part of their appeal is that they strip down for maintenance and cleaning just like their real counterparts! Running gas and BBs through the system obviously doesn't corrode or foul the mechanism like real gunpowder residue, but gas blowbacks still need some maintenance to get the best performance. As the moving parts rub against each other, it is important to know how to keep them moving smoothly and prevent accelerated wear. Far too often people just spray the gun with lube and think that's enough. Thankfully they use silicone oil, so it doesn't actually cause damage. The silicone itself doesn't clean the surface, but the user should clean all moving parts first, and then add a small amount of lubricant. Too much will just attract dirt!

    As you probably guessed already, the WA M4A1 strips like the real thing. You begin by removing the magazine and clearing the chamber. Push out the takedown pin until it's caught by its detent, and tilt the weapon open; the pivot pin acts as a hinge. Pull out the charging handle and bolt carrier a couple of inches, and then pull the bolt carrier out alone. This is enough for regular cleaning. The pivot pin can also be pushed out to disassemble the short carbine into even shorter components (Leon anyone?) for ease of transportation in a smaller pack or even an attache case. As usual, the RIS is unlocked by pulling back on the delta ring, and the sliding stock can be removed by pulling down on the lever while sliding the stock back.

    Know how to disassemble the Colt? You know how to disassemble the WA: Disassembly works just like with the real thing!
    This 210g lump of metal called the "bolt carrier" does a full stroke over 10 times per second, so hold tight!
    The weapon disassembled into the main components. No tools required!


    During the testing phase we were in the same boat as the first customers who bought the WA M4A1: It obviously doesn't use AEG magazines, so we only had the one supplied with the weapon! Of course success on the fielrd depends heavily on the playing style and how you apply it in the field, but 50 rounds is a bit limiting unless you have a fully blown sniper rifle to make every shot count.

    Despite the lack of volume of fire in one magazine, the WA M4A1 is definitely skirmish-worthy. The chrono readings were in the high 300's, which is at the top of the limit for most people's "comfort zone" in CQB, and actually useful even for woodland engagements. Colder climates will be a limitation, as is the case with all guns that use liquid charge propellants. The consistency proved excellent for a gas gun, which probably is due to the refined floating valve that controls the amount of gas used to shoot the BB. Consistent velocities together with a good hop-up system are the two most important things to make an airsoft gun accurate, and this carbine delivered both as you can see from the targets below. The shooting was done from a sitting position with the standard iron sights, using KSC 0.2g Perfect BBs and Green Gas.

    The inner barrel stops 53 mm short of the outer barrel, so there's room for a longer inner barrel to improve the velocity even within the normal outer barrel. G&P has released longer one-piece steel outer barrels as well as full front sets in various configurations, and Inokatsu has announced M16 and XM kits in the spirit of the Vietnam war, so you have all the more options to choose from already. We hope to see inner barrels for this carbine from PDI soon, and Airsoft Surgeon has also performance- and durability-enhancing parts in the works.


    Even if an AEG with a hicap magazine is more convenient for gaming in any weather, everyone at RedWolf has been waiting for long arm that would provide a better feedback and more realistic operation. While many AEG manufacturers have jumped on the mock blowback bandwagon, the Western Arms M4A1 CQB-R blows them all away. The recoil and sound of this carbine is so intense that we haven't seen anyone shoot this and not smile after the first shot.

    Slight teeting problems have been noticed, such as accelerated wear of the bolt hold open. This feature can be disabled, but admittedly that option would take a bit away from the realism, which is an important part of the appeal of this weapon. Thankfully the aftermarket parts supply has kicked in with full force, as if they knew already that this weapon is going to be a hit (Pun intended). With a good reliability and great accuracy out of the box, it has been better than we dared to hope for from a gas blowback shoulder-fired weapon. It won't wipe AEGs out of existence, but finally the realism-minded people have a skirmishable option that suits their needs.

    A 51 mm grouping of five shots from 10 meters before any preparation.
    A better accuracy was achieved after run-in and cleaning: Five shots within 26 mm (center to center) from 10 meters!