G&P XM177E1 AEG High Cycle Custom Part 1

This time, we'll continue customizing the G&P XM177E1, which we disassembled in the previous post.

We decided on the direction of the customization last time, so as a review, I'll introduce the customization direction and the parts we'll be procuring.

Please note that there are fewer photos this time because the customization was completed on a shorter deadline than requested.

Customization direction and sourced parts

First, as a review, I decided on the following direction for customization.

We will procure the parts according to this goal.

The parts we procured are as follows:

We will also be using consumables such as grease and connectors.

I changed some of the parts during the customization process, so I will introduce the final specifications again at the end of the customization article.

Basically, I'll be using the parts I previously planned to use for the ICS Sportline M4, with some original parts being reused.

With this component configuration, I predict that the finished product, using a 7.4V LiPo battery and 0.2g BBs, will have a muzzle velocity of around 92m/s and a rate of fire of about 25 rounds per second, which is a typical high-cycle setup.

We will proceed with the customization.

We'll start by customizing the delta ring to make it easier to install and remove the handguard and battery.

Custom Delta Ring

My initial plan was to disassemble the delta ring and replace the spring, but the barrel nut holding the delta ring in place was too tight to remove, so I had no choice but to cut the spring using a method that didn't require disassembly.

Incidentally, the springs used are not the more easily imaginable coil springs, but rather what are called disc springs (wave washer springs).

As a side note, these disc springs are very difficult to design and handle because it's hard to control the load in relation to the spring's deformation and they have high hysteresis (they have various applications, such as being found in motorcycle clutches).

However, from a space perspective, this type of spring is suitable for use in confined spaces like this one.

First, to access the spring, we'll remove a part called an internal circlip.

Since it might be difficult to understand from just the picture, let me briefly explain what a circlip (there are internal and external types) is: it's a mechanical component used for positioning and preventing shafts from coming loose, as shown in the following diagram (a considerable number are used in automobile engines).

In this product, a circlip is used to hold the disc spring in place.

While circlips are a convenient mechanical component, they require a special tool called circlip pliers to remove, which can be somewhat inconvenient.

I recommend a multiplier that can be used for both internal and external connections, like the one shown below.

Snap ring pliers set
I don't use it very often, but it's frustrating when it's needed and I don't have the right tools (it's often used in hop-up chambers). So having a cheap set is convenient.

Circlips themselves aren't used very often, so you don't get many opportunities to use tools for them, but they're a troublesome thing that you absolutely need to remove and install circlips.

I haven't found a general-purpose alternative tool yet, but I'll share any ideas I come across.

Returning to the XM177E1, once the circlip is removed, the disc spring becomes visible.

The disc spring consists of three plates, and each spring is joined together by spot welding.

To reduce the load here, we'll cut the welded section and reduce the number of disc springs.

Removing too many will loosen the handguard's mounting, so we'll only remove one.

This disc spring is made of iron (spring steel), which is quite hard and durable, so I'll cut it using a powerful rotary tool with a diamond cutter attached.

When cut, it becomes two disc springs as shown in the following picture.

These are wreckage.

There will be metal shavings from the processing, so clean it up. Also, the cut surface is unpainted and prone to rust, so paint it with a marker or something similar.

Finally, put the circlip back in, reassemble, check the load, and you're done.

After checking the assembly of the handguard, it's still a bit stiff, but it's a reasonable level of stiffness, so I'll consider it a success (even a woman could manage it, and there's no wobbling of the handguard).

By the way, the diamond cutter used for cutting the spring is the following product (please pay attention to the shank diameter; it won't fit on the rotary tool if the diameter doesn't match). I'll explain later, but it's also used for cutting sector gears.

• Diamond cutter, shank diameter 2.35mm
It's very useful for machining iron-based parts such as gears. A hard diamond is recommended if possible.

Since it's a consumable item, I think a cheap one will be sufficient.

I'm planning to write an article introducing the tools I use, where I'll explain the details, but to just introduce the product, it's the Dremel high-speed type (I'm a Gundam fan, so I mistakenly call Dremel "Domel").

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 tool comes with many bits included from the start, and its power is incredible, so it can do almost anything. Depending on the bit, it can actually be used for milling, drilling, turning, and more. If you really put your mind to it, you can even create your own metal parts from scratch. It's a bit pricey, but I highly recommend it (cheaper ones lack power, take a long time to process, break easily under overload, and have limited continuous operating time, which is inconvenient).

Next, we'll customize the gearbox.

Since it's a standard Ver. 2 gearbox, we'll proceed with the usual work.

Gearbox customization

First, as preparation, we'll polish the sliding parts of the gearbox body.

The area to polish is the part marked in blue in the following photo.

You could polish it with sandpaper, but I find that too much trouble, so I just use a rotary tool with a buffing attachment to quickly polish it (it's the attachment that came with the rotary tool).

Next, to prevent the gearbox from cracking, we round the front corners of the square hole where the cylinder goes.

It's difficult to explain in text, so I'll show you with pictures.

Other side

While this process could be done with a round file, it's tedious, so I'll use a rotary tool with a tungsten bit for this.

Tungsten bits are not included with the rotary tool, so we recommend this one.

Tungsten bit for rotary tool, shank diameter 2.35mm
Tungsten, the second hardest material after diamond, is recommended considering the price. It cuts very effectively.

I don't use extremely strong springs, so the gearbox isn't subjected to heavy loads, but I've modified it to make it last as long as possible.

While I'm using the rotary tool, I'll also cut the gears on the sector gear.

With the current parts configuration, using a Ronex A4 motor with a 13:1 high-speed gear and a 7.4V LiPo battery, the cycle rate is approximately 25 rounds per second, so to prevent piston crash, we will cut 3 teeth from the sector gear.

Furthermore, to prevent piston cracking, we will cut two teeth on the spring's pull side and one tooth on the release side.

Here, we'll color the teeth to avoid making a mistake with the processing area (this time, we'll use pink).

Cutting with a rotary tool (diamond cutter) while holding it directly by hand will almost certainly result in injury, so it's best to clamp it in a vise while processing.

　I recommend this vise. This inexpensive one does the job perfectly well.

Mini vise
It's inexpensive and versatile. For example, you can use it to extend the life of a motor during the break-in period.

After cutting the teeth, the cut surface is carefully finished by hand using a file, and that's it.

This concludes the machining process using the rotary tool.

Finally, wash away any metal shavings that may have adhered to each part, and you're done.

The process up to this point may seem difficult, but it's actually easy and takes less than 15 minutes if you have the right tools, so please give it a try.

Next, we'll work on the electrical system.

Electrical system creation

This time, to shorten the switch stroke, prevent burnout, and improve response, I'm rebuilding the electrical system using MOSFETs, thicker, high-efficiency wiring, and short-stroke switches.

For detailed information on this electrical system customization, please refer to the article on MOSFET installation.

Basically, this time the process will be exactly the same.

Here are photos of the finished product (the wiring has been replaced with Eagle Model's 1.25 sq silicone silver wire).

To be on the safe side, once the electrical system is complete, I strongly recommend temporarily assembling it into the gearbox and checking its operation.

In particular, shortening the trigger stroke can cause the switch electrodes to fail to make contact or to malfunction due to being pressed too far, depending on the trigger pull distance, so be sure to check this beforehand.

Although not shown in the photos, temporarily assemble the cutoff lever to ensure it works correctly.

If you make a mistake, you often lose semi-automatic mode.

As you get used to it, you might be tempted to skip the verification process because it seems tedious, but be careful, because you'll almost certainly regret it someday (I've learned this the hard way).

This time, since it's a front-wired model and the wiring passes through a narrow hole in the upper receiver, we'll install the MOSFET after assembling the receiver, so we'll consider it finished at this point.

Checking the operation of the components installed in the gearbox and adjusting the AOE (Area of ​​Effect).

Next, we'll temporarily assemble each part and test it to check if it works correctly.

First, I'll temporarily assemble the gears to check for any interference with the gearbox (SuperShooter's high-speed gear 13:1).

Next, we check the play on the left and right sides of the piston (using SHS's 14-tooth reinforced metal tooth piston and Laylax's high-cycle piston head).

I noticed there was a bit too much play, so I'm going to adjust the piston width.

The adjustment is very simple: just carefully attach a 0.2mm thick plastic sheet to the piston groove using super glue.

We will assemble this again and check it.

Next, we will check the movement of the tappets.

With SHS tappets, the contact between the bearing and the tappet vanes is tight when the nozzle starts to retract, so I'll modify it to make it smoother.

While it's not an extremely high-cycle design, it should reach around 25 rounds per second, so we'll also be modifying it to reduce the nozzle retraction time to ensure security.

Here are the processed products.

It turned out great.

Next, we will adjust the AOE (Angle of Engagement).

First, we'll do a test assembly to check the current state.

Simply put, AOE refers to the angle at which the piston's rack gear and sector gear begin to mesh. An incorrect angle can cause teeth to skip, so it's a good idea to check it.

This time it just happened to work out well as is.

However, the reason it worked well this time was because I used the piston head that I had previously adjusted using the ICS Sportline M4.

I've already adjusted the piston head with Haneite rubber on another model (ICS M4), so the AOE is now correct.

　In my experience, sector cutting almost always requires adjusting the AOE (Area of ​​Effect) to make it work properly, so you should adjust it.

I recommend cutting a 1mm thick piece of Haneite rubber and gluing it to the cylinder head (using a brush-on super glue).

• Haneite rubber, 1mm thick
I always use it for adjusting AOE (Area of ​​Effect). My aim is to reduce noise by absorbing shocks, and also to improve durability.

This is a recommended super glue.

Loctite Super Glue with Brush
The adhesive is Loctite, which has reliable performance, so I think it's a good choice. The key point is that it comes with a brush, making it easy to use.

Next, we'll adjust the shims, grease each component, and complete the gearbox.

Shim adjustment, greasing, assembly

First, we'll replace the motor's pinion gear.

The pinion gear included with the Ronex motor is likely forged, and the precision of the tooth surface (the way the tooth surface is filled) is not very good, so it will likely squeak and make noise. I recommend replacing it.

I usually use pinions from Laylax, but I switched to a pinion from OPTION NO.1 because it seemed good for the price.

By the way, you will need a tool called a pinion remover to replace the pinion. If you own multiple electric airsoft guns and are considering using a Lonex motor, replacing the pinion will be almost essential, so I will introduce the recommended tools.

Eagle Model Pinion Remover
There are cheaper options available, but since rigidity is crucial for tools like this, I use this sturdy-looking one. It's only about 1000 yen more than the cheaper ones, so it's around 4000 yen, which I recommend.

There are cheaper tools available, but I recommend this one because using a press-fitting machine like this to grip something flimsy will break the tool.

I've heard that Ronex pinions are hard to remove and can break tools, but I've been able to replace them without any trouble.

After that, I adjust it using a thickness gauge according to my usual bevel gear standards.

Details on how to adjust the shims can be found here.

Once you get the hang of it, you can determine the shim size in about 15 minutes. During this time, you can break in the motor.

Introduction to creating a motor break-in stand

Next is my favorite part: greasing.

The greases I used were the usual Bellhammer Gold No. 2 and GAW's extreme pressure grease.

I use Bellhammer for areas where metals come into contact with each other, and GAW for other areas.

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.

GAW G-GREASE
This is a standard grease. It has a lower viscosity compared to the Bellhammer Gold series, so I use it inside the cylinders of both electric and airsoft guns. It's a bit pricey, but the quantity is large, so in the end, it doesn't feel overpriced.

First, we'll grease the gearbox.

opposite side

Next, apply the appropriate grease to each component.

Finally, I apply Tokyo Marui's high-viscosity grease to the spring (AIRSOFT97 M100 unequal pitch spring) to suppress rattling noises.

　

Now, we'll assemble all the parts and it will be complete.

Incidentally, I'm the type who applies a generous amount of grease, and the reason is that although the cycle rate drops slightly, I use more to ensure durability and reduce noise.

Also, even if you use too much grease, the excess will fly off somewhere during operation and settle into the correct amount, so you don't need to be too concerned about the amount of grease.

The gearbox has red plastic anti-reversal latches and trigger retainers to close it, but I feel like they're only useful for taking pictures.

Personally, I didn't feel it offered much of an advantage during assembly, but since some people might want it, I'll just mention it.

• Gearbox Installation Kit
This might be useful for those who aren't used to closing the gearbox. You can manage without it, though.

Now that the gearbox is complete, I'll assemble it into the receiver for a test run.

Trouble occurs

A tragedy occurred when I was assembling the gearbox into the lower receiver.

First, here's the assembled state. The wiring is in the way, so the magazine won't go in until the catch engages.

Close-up of the nozzle

The problem that arose was that the wiring increased due to the MOSFET conversion, and the power wire was thickened to 1.25 sq, so the wiring could not be routed to fit in the available space, preventing the magazine from being attached.

Furthermore, we found that the increased number and diameter of the wires made it extremely difficult to pass the wires through the gaps in the upper receiver, rendering the design unfeasible.

This accident was entirely due to my lack of knowledge about front-wired models and my failure to check the wiring layout.

I was shocked. The electrical system needs to be redone.

Furthermore, when we attached a test MOSFET and operated it in this state, the rate of fire was 25 rounds per second as intended, but the muzzle velocity variation with 0.2g BBs was severe, and the muzzle velocity of 84m/s was lower than expected, so we will revise the specifications.

I suspect the problem is that the cylinder volume is too large relative to the barrel length.

Next time, I'll pull myself together and rework and re-set up the electrical system, and I'll introduce the chamber area and actual shooting performance.

If you're interested, please join me.

This is a highly recommended product, but it seems that it hasn't made much of an impact on Japan, perhaps due to the effects of the coronavirus.

Therefore, I'll introduce some models that are in stock at the time of writing and that I personally like.

G&P AR 9mm SMG AEG
A US military SMG from the Vietnam War era. The M16 receiver combined with the oddly sized 9mm magazine looks really cool.

G&P M16 Vietnam Version
This was a mainstay rifle from the same period as the XM177 series.

G&P M4A1 AEG Marine Corps Model
定番です。