Tokyo Marui CQBR Block 1 Bolt and Lower Receiver Disassembly and Customization

Last time, I introduced the upper receiver in a disassembly and customization section.

This time, we'll be showing you how to disassemble the remaining bolt and lower receiver area, as well as the hammer mechanism unit (Z system) and how to customize it.

We will proceed with disassembling and customizing the bolt.

Bolt disassembly and customization

These are the bolt, buffer, and recoil spring that we removed last time.

We'll start by disassembling the bolt.

To begin disassembling the bolts, remove the two bolts shown in the following picture.

After removing the two bolts, pull the nozzle while removing the carrier key.

The parts that have been removed so far are as follows:

Be careful, as the spring is easy to lose.

Next, remove the stopper that secures the blowback engine.

Now, pull the nozzle in the direction shown in the picture to remove the blowback unit.

Next, we will disassemble the blowback unit.

First, remove the screw shown in the following picture.

Remove the damper (piston cup).

After removing the damper, pull the firing pin as shown in the following picture.

This will reveal the parts inside the blowback unit.

This completes the disassembly of the bolt.

My custom modification here involves adjusting the muzzle velocity, which was rather low in the stock configuration, by replacing the spring (flow valve spring) (other options include N-PASS, etc.).

The springs I use are the high-pressure spring set from Olga Airsoft.

Olga Airsoft High Pressure Springs
It appears to be usable not only with Tokyo Marui's gas blowback M4 but also with their Type 89 rifle.

The contents include three items: an aluminum spacer, a long spring, and a short spring.

The following five types of embedded patterns are available (in order of initial velocity).

Pattern ① Maximum initial velocity: Spacer + long spring

Pattern ② Initial velocity No. 2 Long spring

Pattern ③ Initial velocity No. 3 Spacer + short spring

Pattern ④ Initial velocity No. 4 Short spring

Pattern 5: Initial velocity No. 5 - Spacer + genuine spring

From these options, you'll find a pattern that suits your individual needs and assemble it.

In my previous article, I mentioned that I had changed the inner barrel to a Maple Leaf Crazy Jet Barrel (250mm length, 6.04mm inner diameter) and the hop-up packing to a Maple Leaf Macaron Super Hop-up Packing 50°, which resulted in a good muzzle velocity for pattern 2, No. 2 (around 92m/s with 0.2g BBs, at 30℃ temperature, with hop-up adjusted).

The adjustments in this areaSince there will be differences depending on the individual condition (individual variations, inner barrel, hop-up packing), be sure to check with a chronograph when making your selection..

If you're interested, there's an article explaining how gas blowback guns work, so please take a look.

Pattern ② with long spring

Once the assembly pattern is determined, proceed with assembly in the reverse order of disassembly, applying grease as you go.

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.

The next customization point for the bolt is replacing the part at the rear end of the bolt, called the bolt B (bolt carrier end), with a G&P roller bolt B.

The aim is to improve operability by increasing the sliding properties through the use of rollers. It's difficult to quantify the effect as it's hard to compare it to the original part, but I feel like it's slightly sharper and fuel efficiency has improved.

G&P Roller Bolt B
The rollers should improve its operability.

I can't find the original part, so I don't have a photo, but the original part is a cylindrical component without rollers.

The replacement process is simple, but the screws are tightened very tightly with threadlocker, so you might have some difficulty.

This shows the bolt B (bolt carrier end) removed.

Now, remove the roller attached to the bolt.

These are the disassembled rollers.

These parts have a significant impact on the operation, so we'll assemble them while carefully applying Bell Hammer Gold Grease No. 2.

The remaining parts can be assembled by reversing the disassembly procedure and attaching the bolts.

Finally, apply Bellhammer No. 0 to the sliding parts of the charging handle, and the customization around the bolt is complete.

Since we're at it, let's measure the weight of the bolt and buffer.

Bolt, buffer weight

　

The bolt weighs 220.5g and the buffer weighs 24g, for a total of 264.5g, which is the weight that moves during the blowback. 264.5g isn't particularly heavy; it's about the same weight as the slide of a large handgun, so the blowback isn't extremely heavy. Tokyo Marui likely determined that 264.5g strikes a good balance between operation and blowback feel.

This concludes my customization of the bolt.

I've been customizing with genuine zinc bolts, but as a further customization option, I think replacing the bolts themselves with aftermarket ones is also a good idea.

For example, you can change to a lighter aluminum bolt to improve operability, or to a heavier steel bolt to experience a more robust blowback, or change the appearance (there are also many different bolt designs).

Bolt example (Personally, I trust Orga Airsoft for Tokyo Marui gas blowback M4 series parts)
・ OLGA Airsoft Steel Bolt Carrier
This is a heavy bolt carrier. Installation is as simple as changing the bolts as described in the article.

・Olgasoft Aluminum Bolt Carrier
This is a lightweight bolt carrier. Installation is as simple as changing the bolts as described in the article.

For those who find assembly troublesome, Olga Airsoft offers a service where you can choose your favorite parts and they will assemble the bolts for you.

If your budget allows, it might be a good idea to have several bolts on hand and change them depending on the season or your mood.

Also, not just with the bolt, but to create a heavier blowback feel, it would be interesting to change the buffer to a heavier material with a higher specific gravity (however, this will result in inferior operability and durability).

G&P M4 MWS adjustable aluminum buffer
The blowback weight is adjustable. You can change it to any weight between 25g and 70g. However, please note that increasing the weight will decrease durability.

Furthermore, another part I personally want to replace soon is the charging handle.

- No-brand Geissele-type ambiguous charging handle
Tokyo Marui gas blowback M4 series charging handles use a proprietary standard, so be careful when choosing one. Look for one specifically labeled for the MWS.

As you can see, Tokyo Marui's M4 series gas blowback machine guns have so many aftermarket parts available that you can practically complete them with them, making them quite enjoyable to customize.

Disassembly of the lower receiver, removal of the hammer mechanism unit.

Now we'll start disassembling the lower receiver.

I'll remove the stock since it's getting in the way.

Next, cock the hammer.

As shown in the picture above, pressing the hammer cocks it.

Hammer cocked state

Next, remove the selector switch.

First, set the selector switch to the position between SAFE and SEMI as shown in the following picture (you should feel a slight click).

In this state, press the selector from the opposite side.

This will bring up a few selectors.

In this state, set the selector switch to the SAFE position.

We'll extract the selector from here.

Next, remove the magazine catch.

First, press the magazine catch button firmly.

While keeping the MagCatch button pressed down, rotate the MagCatch counterclockwise.

This will remove the magazine catch.

Next, remove the grip.

If you look at the grip from the back, you'll see a hexagonal bolt, so remove it.

Be careful not to lose any parts when removing the grip (especially the nuts).

Next, we'll open the trigger guard.

Turn the receiver in the opposite direction from what you've been looking at and press the pin shown in the next 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 quite convenient. Moreover, it's designed for handguns but can also handle longer weapons, 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 tools to push the pins in.

Press and hold the pin while rotating the trigger guard to open it.

Next, remove the pin that secures the hammer unit (pay attention to the direction in which you remove the pin).

Remove the screws that secure the hammer unit.

Next, place a pin punch in the gap between the trigger and the lower receiver.

By tapping the pin punch little by little with a plastic hammer, the hammer mechanism unit (Z system) will pop out.

If you persevere until the end, you can retrieve the Hammer Mech Unit (Z System).

This completes the disassembly of the lower receiver.

This is a list of lower receiver parts.

Hammer Mechanism Unit (Z System) Mechanism and Disassembly

Let's take a look at the removed hammer mechanism unit (Z system).

First, the front view.

It's neatly packed in the box.

This is the top view.

You can see that the hammer has rollers attached to it (which has a significant effect on its operation).

Other side

This is a view showing the core components of the Z system.

Since we're at it, let's try activating the Z system in a simulated way.

The image below is a photograph of the moment the bolt stop engages.

Tokyo Marui's introductory video for the Z System is easy to understand, but I've also created a diagram to illustrate it.

This explains the operation of the Z system step by step (since it's a machine, all events should ideally occur simultaneously).

In other words, the impact load when the bolt is stopped is not absorbed by the bolt itself at all, but rather by the spring, which is placed horizontally in the left corner, after being bent and twisted in various directions.

This seems to be how they achieved long durability.

It's a rather interesting mechanism, but as an engine designer, it's a familiar one to me; in engines, it's very similar to the valve train in an OHV engine.

The linkage in the front suspension of an F1 car is also similar to the Z system, although it's a slightly more complex linkage.

Generally, suspensions and dampers are most efficiently used when they receive the load in the same direction as the load itself (as is the case with typical cars and motorcycles). However, since the suspension is located outside the vehicle, it takes up more space overall.

If space is limited or needs to be minimized, levers (components that change the direction of the load) are sometimes used, like in the Z system, to change the direction and position of the load, thereby shifting it to a position where the dampers and suspension can be placed (special vehicles like F1 cars are a typical example).

The drawbacks include the increased number of parts due to the linkage, leading to higher costs, and the fact that the mechanical efficiency of the suspension and dampers will decrease unless they are designed very well (a difficult technique).

Even in this Z system, there is a slight lack of mechanical efficiency, which is evident in the spring, resulting in a considerably high spring load relative to its size. Therefore, designing the spring is quite difficult (the plunger also seems to have strict requirements).

Disassembly of the Z System

Let's return to disassembling the hammer mechanism unit.

Remove the lever for the Z system, which is the main feature (it may already be removed).

Remove the bolt release lever and the slit cover.

In its detached state.

Next, cock the hammer. While pressing the sear shown in the following diagram, pull the trigger.

Once you remove the three bolts, it will split in two and the contents will come out.

Remove the trigger unit.

Remove the trigger spring.

Next, we will remove the internal components of the main unit.

These parts are simply held in place by fitting together, so they can be easily disassembled.

There are no internal organs in the remaining side.

On the other side are the Z-system dampers and safety features.

This completes the disassembly of the hammer mechanism unit (Z system).

This is a complete list of all parts for the Hammer Mech Unit (Z System).

Summary

This time, I've covered some rather complex topics, starting with the bolt and disassembling the lower receiver.

In the section on bolts, I explained them in a little more detail because they are a part that greatly affects performance (adjusting the initial velocity to a moderate level out of the box).

Since there are a wide variety of aftermarket parts available for the bolt area compared to other parts, this article mainly focuses on my own custom modifications, but I intended it to be a reference for various ways of customizing, such as changing the bolts themselves (it's possible to assemble a complete bolt using only aftermarket parts).

So I think you'll have a lot of fun if you choose your favorite parts and assemble it yourself.Compliance with laws and regulations, including initial velocity.).

I wrote this article because I don't think many people will ever disassemble the lower receiver. However, I think many people will be considering changing the grip or selector switch, so I will explain those external modifications in detail in the next article, which will cover assembly.

While I imagine fewer people disassemble the Hammer Mech Unit (Z System), I took it apart out of personal interest and decided to share my findings.

My impression after disassembling it is that realism was compromised in favor of modularization, compactness, and ease of operation.

One aspect that is often mentioned is the hammer shape and operating angle. The hammer's protrusion during decocking is minimized, prioritizing operability, and it even has rollers, which I appreciate as someone whose main activity is airsoft.

Another point is whether the Z system is good or bad, but personally, I prefer higher durability, so I view it favorably.

However, the parts of the design that personally concern me are the load on the "load-transforming components" within the Z system, the strength of the springs, and the strength of the plungers.

Furthermore, the "load-transforming component" acts as a lever, so depending on the lever ratio, it can be subjected to considerable stress, raising concerns about its durability. However, all we can do is wait and see.

Thank you for reading this far.

Next time, I'll show you the process from assembling the lower receiver to its completion.

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.