Disassembly and customization of the Tokyo Marui CQBR Block 1 upper receiver

Last time, I introduced the appearance of the Tokyo Marui CQBR BLOCK1 after it was converted into an MK18 mod.1.

This time, I'll be showing you how to disassemble the handguard, barrel, and hop-up chamber, along with some of the custom modifications I've made.

The unit I'll be introducing is a CQBR Block 1 that has been modified into an Mk18 mod.1 using aftermarket parts. However, since many people are likely considering replacing the handguard on Tokyo Marui's gas blowback machine gun series M4A1, MWS, and CQBR Block 1, I will explain the process with the handguard returned to the original CQBR Block 1 condition.

We'll start by removing the parts around the bolts from the takedown.

Takedown, bolt removal

We will proceed with a standard takedown.

Press the pin at the rear end of the receiver.

Please note that this pin cannot be completely removed to prevent loss. Forcing it out will break it.

Lift the upper receiver.

In this state, remove the bolt and charging handle.

These are the removed bolt and charging handle.

Next, in gas blowback M4-type rifles, the buffer and buffer spring are located inside the stoick pipe, so we'll remove them.

Press down the block that is holding the buffer in place.

Pressing the block will release the buffer and recoil spring that were housed inside the stock pipe.

Remove the buffer and recoil spring, and you're done. The recoil spring is easier to remove if you twist it counterclockwise while pulling, rather than just pulling it straight.

Now you can remove the parts around the bolt. Disassembling and customizing the parts around the bolt will be covered in the next article.

Hop adjustment

The hop-up adjustment mechanism on Tokyo Marui's gas blowback M4 series is located in the upper receiver, so you can't adjust the hop-up without disassembling it this far (you don't need to remove the buffer or recoil spring).

Hop adjustment dial

I tried adjusting the hop-up without taking the gun down, by pulling the bolt and sticking my finger through the ejection port, but I couldn't do it with my hands and fingers.

In this state, adjusting the hop-up after taking down the gun is quite troublesome in airsoft games due to space limitations at the range, limited time, and dust issues outdoors.

LAYLAX has released a lever (Hop Dial Adjuster) that allows you to adjust the hop without disassembling the gun, making this cumbersome hop adjustment process much easier.

This allows you to adjust the hop-up without taking down the gun or disassembling the bolt.

To briefly explain how to use it, first you engage the bolt stopper.

If you stop the bolt and look into the magazine port, you can see the hop-up adjustment dial.

Align the lever with the position of this dial and insert it through the ejection port.

Moving the lever allows you to adjust the hop-up.

This makes hop-up adjustment much easier, so it's incredibly convenient, and personally, I find this lever so useful that I wouldn't even consider taking my CQBR outside without it.

I always use this lever and the CQBR together, so I always keep the lever inside the grip so I don't forget it.

Thanks to this grip, I can avoid problems like forgetting to bring the lever or losing it. However, the original grip is hollow inside, as is typical for gas blowback guns, but it doesn't have a bottom cover, so it can't be used as a small storage compartment, so please be aware of that (if you have the original grip, it's recommended to store it in the original stock).

Furthermore, this hop dial adjuster is convenient because it makes it easier to adjust the hop-up on several of Marui's gas blowback handguns, just like on the CQBR, without the need for a field strip.

Personally, with Tokyo Marui gas blowback handguns, I don't use this lever for hop-up adjustment because it's more accurate, faster, and easier to simply take down (field strip) the gun and adjust the hop-up that way. This is simply because I'm used to field stripping handguns and it doesn't bother me; it might be a convenient lever for those who aren't used to it.

LAYLAX Hop Adjuster
I think this is an essential item for Tokyo Marui M4 series gas blowback pistols. It's very convenient.

Disassembly of the handguard and barrel

Before disassembling the handguard, separate the upper receiver from the lower receiver.

First, press the pin on the front of the lower receiver.

This pin, like the takedown pin, is designed not to be completely removed to prevent loss. Therefore, trying to force it out will break it.

This allows you to separate the upper receiver.

Up to this point, the procedure is the same regardless of the type of handguard.

From here on, we'll start the explanation from the point where the handguards (front rails) have been returned to their original state.

Original upper receiver

We'll start by disassembling the handguard.

First, remove the bolts on the top of the rail.

Next, remove the rail by pulling the handguard ring at the base of the front rail.

This is the gun with the handguard removed.

Next, remove the gas block (the following photos are reversed). First, remove the two pins shown in the following photo to remove the gas block. While you're at it, remove the flash hider as well.

To carefully remove the pins shown above, we recommend using a pin punch, block, and plastic hammer as shown in the following picture.

Signet Pin Punch Set
It's not a luxury brand, but it's a recommended mid-range brand in the automotive industry that offers good value for money. Plus, it's inexpensive.

Eagle Force Maintenance Bench Block for Handguns
It's incredibly convenient to have. Moreover, it's designed for handguns but can also handle longer firearms, making it very useful. In fact, I personally didn't see the need for their M4 version.

Vessel Plastic Hammer
It's inexpensive, sturdy, and long-lasting. For a good balance of control and power, the 1-pound size is recommended.

Use these to remove the pins.

This shows the gas block detached from the barrel.

Next, shift your focus to the barrel base and remove the screw shown in the following photo (disassembly of the barrel dummy nut).

Removing the screws will allow you to remove the barrel dummy nut, handguard ring, and leaf spring.

Next, we'll remove the barrel base nut (this is the tricky part).

This barrel nut is tricky; it's impossible to disassemble it with general-purpose tools, and a special M4-type wrench is required. Also, regardless of the manufacturer or whether it's electric or gas-powered, the barrel base nut on M4-type guns is often fastened very tightly, so I use a fairly heavy-duty wrench. As you can see, it's quite heavy, but since it's not a tool I carry around, I prioritize sturdiness and ease of use.

• Multi-wrench (combo wrench) for M4, M16, and AR15 bolts
Having this when working on AR-15 series rifles, including the M4, greatly expands the range of customization options.

If you manage to remove the barrel base nut with a wrench, it will look like the following picture.

This completes the disassembly of the front section.

Finally, here's an overall view of the handguard and rail components.

Disassembly and assembly of the barrel and hop-up mechanism.

From here, we'll disassemble it from the barrel to the hop-up chamber.

First, remove the outer barrel (including the inner barrel and hop-up chamber). The outer barrel is simply inserted into the upper receiver, so it can be removed by carefully pulling it.

Remove the inner barrel and hop-up chamber from the outer barrel.

This is an overall view of the inner barrel and hop-up chamber.

I replaced the inner barrel with a Maple Leaf Crazy Jet Barrel for gas blowback 250mm and wrapped aluminum tape around the tip to prevent barrel wobble.

The inner barrel has a standard length of 250mm, and the standard hop-up is the same as that of Tokyo Marui's typical gas blowback pistols.

Therefore, if you choose based on a barrel length of 250mm (the original barrel length), you should be able to install custom barrels for gas blowback guns from other manufacturers. So, when replacing the inner barrel, I think it's fun to choose one that suits your preference while considering the length relative to the outer barrel (VSR10 barrels are also compatible).

Among the various manufacturers, I often use Maple Leaf's Crazy Jet barrels. The reason is that I don't really believe the claim that the airflow from the air sleeve improves the trajectory, as stated in the product description, but I like the shape of the hop-up window and the precision of the manufacturing, so I use them.

Maple Leaf Crazy Jet Barrel 250mm for Gas Blowback Guns
I think the stock barrel is perfectly fine, but I used a Crazy Jet barrel and matched the length to the stock 250mm.

- Aluminum tape, 0.1mm thick
It's almost like a magic spell.

Next, we will disassemble the hop-up chamber. The hop-up chamber is secured with O-rings and no bolts, so carefully slide it apart, taking care not to cut the O-rings.

This is a disassembled hop-up chamber (the photo orientation is reversed).

My approach to hop customization prioritizes a flat hop configuration, so the parts I use in my hop chamber are as follows.

Maple Leaf Macaron Soup Hop Packing 50° for Gas Blowback and VSR10
This is what I chose when I customized my car (in 2021). Nowadays, the company also offers improved gaskets, so it's up to your preference.

Maple Leaf Omega Action Rubber
It works quite well when combined with a flat hop-up. Although it's labeled for electric airsoft guns, it can be installed in the hop-up chamber of Tokyo Marui M4 series guns.

- Aluminum tape, 0.1mm thick, double layer
I mainly use 0.25g BBs in my setup, so this will increase the bulk.

This setup produces a pretty good trajectory. However, since it's a complete flat hop setup, hop adjustment becomes tricky, and it seems that it doesn't perform as well with BBs heavier than 0.25g, so I recommend carefully selecting parts and enjoying the process.

Alternatively, you might find it interesting to choose hop packings from Miyagawa Rubber, a representative example of long-range hop packing, or from other companies with shapes similar to the original equipment.

Even if you don't get a good trajectory as a result of these parts selections, you can always revert to the original settings, so I think you'll have even more fun trying again.

Next, we will disassemble the hop-up adjustment mechanism, which also functions as a bolt damper.

First, remove the bolt located at the top of the front of the upper receiver.

This is the removed hop-up adjustment mechanism and bolt damper.

Other side

As shown in the photo above, the plunger attached to the hop dial to give it a click feel is easily lost, so please be careful.

This part can be disassembled by removing the Phillips head screw shown in the photo above.

Exploded view

This completes the disassembly of the upper receiver's front section (including the inner barrel and hop-up chamber).

Barrel and hop-up chamber assembly

Now we'll start assembling the parts we've disassembled.

Since we're going to disassemble and reassemble it anyway, we'll use two different types of grease to apply them.

Bellhammer No. 0 Gold Grease
This is a classic, top-quality grease. No. 0 is a low-viscosity grease. I generally use No. 0 for resin-to-resistance and resin-to-metal connections.

Bellhammer No. 2 Gold Grease
This is a classic, top-quality grease. No. 2 has the same ingredients as No. 0 but with a higher viscosity. I primarily use it for metal-to-metal connections.

First, apply Bellhammer Gold Grease No. 2 to the hop adjustment mechanism and bolt damper and assemble it.

To make hop adjustment even easier, I used a file to engrave an arrow on the underside of the hop dial indicating the direction in which the hop effect will be stronger.

We will now assemble this into the upper receiver using the reverse procedure of disassembly.

Next, we'll assemble the inner barrel and hop-up chamber.

First, apply silicone grease around the hop-up window of the inner barrel (to improve airtightness).

This step is not performed if the hop packing material is silicone rubber, as it will cause the rubber to swell. A way to identify silicone rubber is to look for a semi-transparent color; this indicates a high probability of it being silicone.

AZ Silicone Grease
This is a standard product from AZ. While Tokyo Marui's genuine grease is sufficient, this is recommended because the quantity is small. It's also inexpensive.

Install the hop packing here and wrap it with sealing tape as shown in the next picture (to improve airtightness).

KAKUDAI Seal Tape
This is a standard product for all airtight applications.

Next, assemble the hop arm, maple leaf omega cushion rubber, and aluminum tape, applying No. 2 grease.

Next, assemble the hop chamber using the same procedure as disassembly and check how the hop-up drops.

If the hop-up is working correctly, assemble the inner barrel, hop-up chamber, and outer barrel, then insert the barrel into the upper receiver, and you're done.

Installation of the Mk18 RIS2 handguard (handguard replacement)

From here, we'll be using the aftermarket Madbull Airsoft Daniel Defense-licensed Mk18 RIS2 9.5-inch handguard as an example to replace the handguard.

Madbull Airsoft Daniel Defense Licensed Mk18 RIS2 9.5 inch
I think it's one of the standard handguards.

Besides the Mk18-type handguard I introduced, I believe that popular M-LOCK handguards like the URG-I can also be attached using almost the same method. However, since the screw specifications at the base of the barrel are unique to Tokyo Marui, choosing a handguard designed for electric airsoft guns will likely result in a smoother installation.

First, let's take a look at the contents of the Madbull Airsoft Daniel Defense Licensed Mk18 RIS2 9.5-inch airsoft gun.

These parts alone are not enough to assemble the rail, so a barrel nut spacer is also required.

First, let's look at the barrel base.

Depending on the model, the barrel base may not have a hole for the gas pipe, so drill a hole if necessary.

While a rotary tool would make drilling easier, for cost reasons, you can use a drill bit set and drill small holes by hand, gradually increasing the size.

Dremel High-Speed ​​Rotary 4000
This is my go-to rotary tool that I always use. Having this expands the possibilities of your DIY projects. There are two popular models, the 3000 and the 4000, but I recommend the 4000 because it comes with a set of tools and has more power.

This barrel base is then assembled by inserting the barrel into the upper receiver.

Next, we'll use the barrel nut spacer.

ORGA M4 MWS barrel nut spacer
I used Olga's product, but similar parts are also sold by other companies such as GAW.

This part plays an important role.

This spacer is used to secure the outer barrel because the outer diameter of the outer barrel is often smaller than the inner diameter of the barrel base nut included with aftermarket handguard sets, not just with Madbull Airsoft products.

It was probably just a coincidence, but it was the perfect size, so I didn't need to use any additional shims (like washers).

Attach the barrel base nut included with the rail set on top of this.

This part is then attached to the upper receiver via the outer barrel.

Tighten this barrel base nut with the M4 multi-wrench introduced in the article.

Next, we'll assemble the gas block.

This time, since using a triangular post-type gas block like the genuine part would prevent the rail from being assembled, we will use an aftermarket low-profile gas block (the gas pipe is a mass-produced type).

No-brand Daniel Defense Low Profile Gas Block
Any low-profile gas canister should be fine. Also, if you're not concerned about realism, you could choose not to include a gas block.

I assembled the gas pipes into the gas block. The included pins didn't fit the hole diameters of the gas pipes, so I used toothpicks to secure them.

Attach this to the outer barrel and tighten the two fixing bolts.

When installing the gas block, make sure that it is perpendicular to the upper receiver during assembly.

With this, the preliminary preparations for installing the rails are almost complete, so we will now install the top rails.

Before bolting the top rail in place, use the scope mount or red dot sight mount in this position to ensure the rail is installed straight.

We intentionally position the mounts so that they straddle the receiver and front rail.

Now, tighten the bolts that secure the rails (there are 6 in total).

Other side

荳

This completes the installation of the top rail.

Remove the mount and check that the rail is flush and straight against the receiver.

側面

Above

Once you've confirmed that everything is assembled straight, the last step is to assemble the bottom rail.

In the case of the Mk18 RIS2, it is secured with three slotted bolts on each side, for a total of six slotted bolts on both sides.

Finally, attach the flash hider and you're done.

Complete

Other side

This completes the handguard replacement.

Summary

This time, I've put together a detailed and lengthy explanation covering everything from disassembling the upper receiver to replacing the handguard.

In the article, I changed to the rail of my favorite Mk18 mod.1, but I think the process will be similar when changing to other handguards such as M-LOCK type (represented by URG-I), KeyMod, or various civilian types.

Regarding the barrel length, I kept it at the stock 10.3 inches of the CQBR Block 1, but since compatible outer barrels are sold by third-party manufacturers, it might be interesting to try changing the length.

Furthermore, while the trajectory is excellent even in its stock configuration, I think one of the great joys of using this gun is being able to change the inner barrel and hop-up packing to customize the trajectory to your liking.

As you can see, one of the great joys of M4-type (AR15-type) airsoft guns, whether gas blowback or electric, is the ability to change the handguard, inner barrel, and hop-up packing to adjust the trajectory, so I've tried to explain it in detail.

In particular, the M4 series of Tokyo Marui gas blowback machine guns has been on the market for over 7 years and is becoming the standard for gas blowback guns, just like the real M4. There are also many aftermarket parts available, so I think you'll enjoy them quite a bit.

The article is long, but the actual work should only take about two and a half hours if everything goes smoothly, so if you're interested, please give it a try (although the manufacturer does not recommend it).

That's all for now; thank you for reading this lengthy explanation.

Next time, I'll show you how to disassemble and customize the bolt, lower receiver, and hammer unit.

Tokyo Marui Gas Blowback Machine Gun Series CQBR Block 1
This is the base model introduced in this article. You can use it as is, or I think it would be good as a custom base for a 10.3-inch short model (such as a short URG-I).

Tokyo Marui Gas Blowback Machine Gun Series M4A1 MWS
This is the basic M4 MWS. It's so good that it would be a shame to customize the rails, so I think it's best suited for users who want to use it as is. It would be fun to customize the grip, stock, etc. to your liking.

Tokyo Marui Gas Blowback Machine Gun Series M4A1 Carbine
This model is the cheapest in the series, so if you're planning on customizing it, I think it's the best choice (though it's perfectly enjoyable as is). You can do anything with it, from changing the rails to altering the barrel length to make it similar to an SR25.

Tokyo Marui Gas Blowback Machine Gun Series Mk18 mod.1
This is a perfectly finished model. If it had been announced before I made my purchase, I would have bought this one too.

- Spare magazine for Tokyo Marui M4A1 MWS (compatible with the series)
This is a standard 35-round magazine. I use the one that comes with the gun plus four additional magazines for a total of five. Having five gives you plenty of leeway, so I recommend adding four more, but depending on your budget, you can still enjoy the game with just three additional magazines.

- Tokyo Marui Gas M4A1 Series 20-Round Short Magazine (Compatible with the Series)
With a 35-round magazine, it sometimes touches the ground when prone, so I think it's good for marksmen and snipers who often use the weapon prone.