Customization and Mechanism of the Tokyo Marui CURVE Fixed Slide Gas Gun

In the previous article, I disassembled the Tokyo Marui CURVE.

This time, we'll be assembling it while customizing it.

Normally, I would summarize any areas for improvement I noticed during the review and disassembly process, discuss possible solutions, and then introduce the actual work process. However, this product is so simple and well-designed that there weren't any major points of concern.

The main focus of this customization will be polishing and greasing parts to improve the feel of the operation.

Since this is a great opportunity to assemble it, we will provide a detailed explanation of the assembly process, introduce some interesting custom parts, and also explain the firing mechanism of this product.

Custom trigger and hammer mechanism

First, we polish the chassis that houses the launch mechanism.

On the left side of the chassis, polish the parts where the trigger and hammer slide.

The right-side chassis is also polished, specifically the parts where the trigger and hammer slide.

I polish it all at once using a rotary tool's buffing pad. If you don't have a rotary tool, you can polish it with coarse sandpaper.

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.

After polishing, the finished product will look like the photo below.

Inside of left chassis

Outside

Inside of the right chassis

Outside

Next, we will assemble the trigger unit. If you have already disassembled the trigger unit, please refer to the following photos to assemble the unit.

Apply grease to the moving parts as you assemble it onto the right-side chassis. Once assembled, hook the hammer spring into its designated place as shown in the picture below.

I'll use my usual go-to grease, Bellhammer No. 2.

Bellhammer No. 2 Gold Grease
This is a classic, top-quality grease. I primarily use it for metal-to-metal connections.

We'll also assemble the hammer.

Once you sandwich it with the chassis on the other side and tighten the screws, the mechanical part is complete.

Resin parts (safety features on other models, not used on the CURVE) and three fastening screws.

Attach the trigger.

Next, we'll install a spring into the trigger to give it a clicky feel.

Now we'll assemble the trigger bar. When assembling the trigger bar, hook the spring onto the bar.

This completes the assembly and customization of the mechanical parts.

Before we finish, let's explain the launch mechanism of the CURVE.

Mechanism of the Compact Carry Gas Gun Series

First, let's explain the ammunition feeding mechanism.

The CURVE Compact Carry Gas Gun series features a nozzle function integrated into the magazine.

When a bullet is actually loaded, the bullet is ejected by the back-and-forth movement of the nozzle.

The bullet, fed from the magazine, is then fed into the hop-up chamber and inner barrel, and when the magazine valve is struck, it is fired.

Interestingly, many of the functions necessary for firing are located in the magazine and inner barrel.

Now, let's look at how the chassis's mechanical components control the movement of the magazine nozzle.

The magazine nozzle is connected to the trigger via a loading plate.

When you pull the trigger, the loading plate moves and advances the nozzle.

This mechanism allows for ammunition to be fed in conjunction with the trigger.

Next, we'll look at the relationship between the trigger and the hammer, and the half-cock mechanism.

The trigger is connected to the hammer by a trigger bar.

As you pull the trigger, the trigger bar and the chassis engage, creating a half-cocked state, as can be seen in the photo above.

Pulling the trigger further from the half-cocked position (where the chassis and trigger bar are engaged) will cause the hammer to fall, eventually releasing and striking the magazine valve.

With its minimal parts configuration and simple structure, it's truly a testament to Tokyo Marui's craftsmanship. It's so simple that I could hardly think of anything to customize it.

With such a simple and modular structure, I think it's possible to create a variety of product variations at a reasonable price, so I'm looking forward to future developments.

Exterior assembly

Now that the Hammer Mech chassis is complete, I'll start assembling it onto the frame.

We'll install the safety features into the frame.

It is assembled.

We'll now install the Hammer Mech chassis into the frame.

Secure the hammer mechanism chassis and frame with three screws.

Next, we'll assemble the front cover.

Simply put the lid on and secure it with screws, and you're done.

I decided against it this time, but there's a fairly large space inside the front cover, so with some ingenuity, you could probably install a light unit or something similar (like a light that uses LR44 batteries from a 100-yen store). After doing some research, it seems that Burst Head sells light units, so if you're interested, check them out.

Next, we'll assemble the outer barrel. The outer barrel is secured with two screws.

If you'd like to attach a suppressor or other accessories to this outer barrel, DNR seems to sell compatible parts. Also, Burst Head seems to sell slides with silencers and rails, so check them out.

- Silencer adapter unit for DNR CURVE
It looks easy to install, and the shape seems to minimize the chances of getting a defective product.

Next, we'll assemble the inner barrel.

I'll use a file to remove any burrs or sharp edges from the inner barrel hop-up window. It's not a variable hop-up model, so it won't have much effect, but I'll do it for peace of mind.

The tool you'll use is a round file. Use the round file to smooth the edges of the hop window.

Diamond file set
These diamond files offer great value for money. The round files, in particular, are very useful. The 5-piece set is highly recommended.

Before assembling the hop-up packing, apply silicone grease to improve airtightness. However, the packing on this product is quite tight, so I think it won't make much difference even if you don't apply silicone grease (it's more of a psychological thing).

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

Install the sleeve in front of the hop packing.

Carefully install the hop packing.

Finally, attach the hop-up arm to complete the inner barrel.

Custom parts related to the barrel and hop-up include adjustable hop-up kits, tight barrels, and long barrels. Personally, I think the muzzle velocity of this model depends heavily on the gas output of the magazine, so I don't think there's much benefit to changing the above parts, but feel free to take a look if you're interested.

DNR Tokyo Marui CURVE Screw-type HOP Chamber
It seems like it would be difficult to install and adjust. However, if you're doing a major overhaul to increase the muzzle velocity and use heavier ammunition, I think it would be a useful item.

TN barrel for Tokyo Marui CURVE
This is a tight barrel with an inner diameter of 6.04mm. It is available in the standard length and a longer 80.5mm version (approximately 20mm longer than the standard barrel).

If you want to increase the muzzle velocity, you could modify the magazine to increase the gas output and lengthen the barrel, but I think it would become too large to be a compact carry gun anymore, so I'm personally going to pass on that (you would enlarge the hole diameter of the magazine valve, strengthen the hammer spring, and hide the barrel that protrudes from the longer barrel with a silencer).

Regarding the hop-up, there is some adjustment range even with the stock setup, so if you fix the weight at 0.2g, it should be able to compensate for temperature differences and differences in brand (unless you increase the muzzle velocity and use heavier BBs).

Next, install the inner barrel into the frame. Don't forget to tighten the grub screw that secures the inner barrel at this time.

Next, place the loading plate and attach the slide, and you're done.

slide

It might be interesting to replace the original slide with one that comes with a rail and silencer adapter.

・Tactical slide for BURST-HEAD CURVE
It seems like a good deal because it comes with a rail and silencer adapter. It comes in four colors: black, orange, white, and olive drab. Since it's probably 3D printed, the texture isn't a major concern, and it's probably best suited for those who aren't particular about the design of the original slide.

And that's it! (I forgot to attach the clip.)

Summary

Since I didn't decide on a concept beforehand for this custom build, I only polished the moving parts, greased them, and carefully assembled the hop-up packing. I didn't do any customizations that would affect the muzzle velocity, so I'll skip the performance check.

While it's a simple modification that doesn't affect the initial velocity, it significantly improves the feel of the operation. Fixed-slide gas guns have heavier triggers compared to blowback models, so trigger feel greatly impacts accuracy, making this modification highly recommended.

This model, in particular, has a simple structure, making it easy to disassemble and assemble. Once you get the hang of it, you can do it in under 30 minutes. The customizations I've described don't cost much money, so I recommend it (all you need is sandpaper and silicone grease).

Although I decided against it this time, I did introduce some interesting custom parts in the article, so if you're interested, please give them a try. I tried to explain the assembly process carefully in the article, so it should be helpful as a reference for installing the parts.

Thank you for your time.

Tokyo Marui Compact Carry Gun No. 4 CURVE Fixed Gas Gun
The actual market price is 6980 yen, so you can use it as is, or I think it's also perfect as a base for customization.

Tokyo Marui CURVE Spare Magazine
It's not a model that fires in rapid succession, but since it only holds 10 rounds, it would probably be more practical to have a spare.