UMAREX/VFC G45 (Glock) Customization Completed

In the previous custom build introductions, we finished modifying the hammer unit and hop-up system.

This time, we will complete the remaining adjustments and then perform a live-fire test.

Custom work details

Let's start with the slides.

Slide adjustment

First, before assembling the parts into the slide, we'll place the original slide against the chassis to check the fit.

I felt the movement was a bit stiff, so I'll be making some adjustments.

Let's take a look at the grooves on the slide in its original condition.

My guess is that either the thickness of the coating wasn't considered during the design phase, or the coating thickness wasn't properly controlled during manufacturing, resulting in a thicker film and a stiffer operation.

While it might seem that paint films are insignificant and irrelevant to most products, the paint films on industrial products are often around 20μm to 50μm (0.02 to 0.05mm) thick, which is thicker than a human hair (about 0.05mm).

I think it's easy to imagine that if a strand of hair gets caught in a sliding surface, the movement will become sluggish.

When designing machinery, you have to be careful about the coating when determining the base dimensions, otherwise you might make mistakes. It's quite a challenging job.

Anyway, the movement is sluggish, so I'll modify it.

I'll buff it with a rotary tool. The goal is to buff it enough so that the paint comes off.

After processing

This is where my skill comes into play; I proceed carefully, making sure not to affect the appearance or remove too much material.

I'll assemble it again and check it.

It's gotten much better.

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.

Next, we'll assemble the blowback engine.

Blowback engine assembly

This time, I wasn't asked to adjust the gas discharge balance, so I'm just checking the parts, applying grease, and assembling them.

Since these parts are basically used in combinations of resin-to-resin or resin-to-metal, apply Bellhammer Gold Grease No. 0 to the moving parts and assemble them carefully.

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.

Piston cup, around the breech

Flow valve inside the nozzle

Assemble these parts into the slide and check that the nozzle moves smoothly.

The blowback engine installation is now complete.

I've written an explanation of the operating principle of gas blowback guns on this blog, so if you're interested, please take a look.

Complete

Finally, grease the recoil spring.

Compress the spring to gain access to the sliding parts and apply grease (Bellhammer No. 2).

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.

This type of guide has a double spring and many sliding parts, so lubricating it with grease will significantly improve its movement, which is why I recommend it.

Next, apply grease to the remaining moving parts and assemble.

Since I applied a generous amount of grease, I manually operated the slide to wipe off the excess grease, and then it was finished.

Next, we will check the live-fire performance.

Live-fire performance verification

We will check under the same conditions as usual.

Fill the magazine completely with HFC-134a gas and raise the surface temperature to 27.2°C. The room temperature is approximately 22°C.

The muzzle velocity will be measured using G&G 0.2g bio BBs.

First, set the hop gauge to 0.

It's okay.

Now, we'll set the hop amount to maximum.

Personally, I feel like it went exactly as planned.

Furthermore, at the customer's request, we will also test it with 0.23g BBs.

Hop quantity: 0.

Those are reasonable figures.

The hop amount is at maximum.

It's a pretty good result.

If you're interested, please also check out my review of the chronograph.

Next is fuel efficiency.

Fuel efficiency

This is the weight of the magazine when it is full of gas.

This is the weight of a magazine after firing all 22 rounds.

The total gas consumed for 22 shots was 2.5g, which works out to 0.11g per shot.

Before adjustment, each shot weighed 0.23g, so it's now less than half. For reference, from what I've researched, handguns typically use around 0.2g BBs.

That's a pretty amazing number.

Since this was only performed once as a sample, it's not very reliable and should be treated as a reference value only, but the fact remains that this number was obtained.

Next is a video of it in operation. As expected, the movement has improved considerably.

UMAREX/VFC G45 Operation Video After Adjustment

For reference, this is before adjustments.

UMAREX/VFC G45 Operation Video Before Adjustment

If you compare them, you'll see the difference.

Both tests were conducted under the same conditions: room temperature of 20-24°C, using magazines that had been completely emptied.

With this, the product is complete and returned to the customer.

G&G Bio-Bullets 0.2g
It's inexpensive and accurate, so I use it for a wide range of purposes, from performance testing to airsoft games. It's been my favorite since it first came to Japan (around 2008). It lasts a long time for a biodegradable product.

G&G Bio-Bullets 0.25g
It's 0.25g. I generally use 0.25g BBs when playing airsoft.

Customer's operational and ballistics verification results

The customer has confirmed the operation and ballistic performance, so we will record the results.

I was surprised to hear from the customer, after they checked the operation, that the hop-up was too strong, causing the BBs to jam and the gun to not work even with the hop-up adjustment at 0.

I was relieved to hear that the hop-up arm worked normally after the customer removed the 0.2mm plastic plate they had added.

I believe the cause was that the diameter of the bullets varied slightly depending on the brand.

Next, when they checked the trajectory, they said that even with a hop-up setting of 0, the hop-up was too strong with 0.2g BBs.

The customer also prepared a new genuine hop arm and hop packing, specifically Maple Leaf hardness 60 (yellow), and inserted a 1mm thick piece of rubber between the packing and the arm, which apparently yielded fairly good results.

Even so, they said that with 0.2g BBs, setting it to the 15th of 20 adjustment levels was about right, so it might still be a little weak (I'm worried about how it will perform in the summer).

I sincerely apologize for the great inconvenience I caused. Moreover, I was helped by your wonderful ingenuity, and it made me realize once again how much I still have to learn and feel humbled.

I am filled with gratitude.

However, in order to move forward, some consideration is necessary, so I will try to think about the reasons why a difference occurred between my operational checks and the customer's operational checks.

<Additional Information>

After the article was published, we received information from a customer regarding the trajectory, and they reported that they had significantly improved the results by switching the hop-up packing back from Maple Leaf to the original and inserting a 1mm thick rubber sheet between the hop-up arm and the packing.

With 0.2g BBs, the correct hop-up setting was achieved at 10 clicks out of 20, and with 0.23g BBs, it was achieved at around 14 clicks. With 0.23g BBs, the trajectory remained low up to about 30m.

Also, it seems that the packing for the Maple Leaf in this particular model was slightly larger than the chamber.

Indeed, Maple Leaf packings are slightly larger than standard gas blowback packings, so be aware that compatibility may vary.

From my experience, handguns fit in a tight fit, while longer guns can just about fit (the WE SVD is a bit of a tight fit).

Analysis of the cause

Basically, to avoid variations in indoor environments, when I test live-fire performance, I set the room temperature to 20-24°C and the magazine temperature to around 28°C, which is below body temperature, to collect data (I generally assume the target temperature is 20°C or higher).

However, in reality, it is used in a variety of outdoor environments, and at the time of this article (end of November), it is likely to be used when the outside temperature is between 10 and 12°C.

I suspect the main reason for the difference is the change in rubber hardness due to temperature (based on my experience as a designer, it changes quite a bit).

Naturally, lower temperatures cause the rubber to harden and increase the coefficient of friction, so I believe this is why the same amount of hops results in stronger adhesion compared to summer or indoors.

I'm sure many of you have experienced this during airsoft games: you perfectly adjusted the hop-up in the morning, but then in the warmer afternoon, you noticed that your shots didn't fly as far as you expected, even though you hadn't changed it.

Another point, though it's an excuse, is that my basic hop-up setting aims for a strong setting (to accommodate heavier BBs) where the hop-up adjustment is around 0, making it suitable for 0.2g BBs. I also heard that you were using 0.23g BBs, so I adjusted the hop-up a little stronger, which backfired.

Also, since I personally don't play airsoft much in the winter, I think it's not good that I have less ballistic data from the cold season.

I will keep this lesson in mind.

If you wish, we can make any fine adjustments to the hops, so please let us know if you would like to make any changes.

Recipe and summary

First, here's the recipe.

Summary

The product was usable even before adjustment, but by sticking to the basics and performing some simple, straightforward work, I think its performance has improved considerably.

I'm not doing anything particularly special, but I think it's the accumulation of small details that makes the difference. Especially with overseas products, there are some areas where the finishing touches are slightly lacking, so if you do things carefully, you can see a big difference, which is satisfying.

Furthermore, not only are overseas products lacking, but even domestic manufacturers produce mass-produced items, so there are some areas where they fall short. Making some minor adjustments can improve them slightly. This improvement is particularly noticeable with older items.

This time, we worked based on data from the Glock 19X, but due to differences in model specifications and individual variations, we caused problems with the hop-up, so there are many things we need to reflect on.

This experience has reinforced the importance of collecting data broken down by season and temperature.

However, adjusting the hop settings is often difficult and cannot be determined solely through theoretical study or indoor testing. I may have become overconfident recently, as I've been able to get the hop settings right on the first try.

Finally, I would like to express my sincere gratitude for the permission I received to post this on my blog, and for the helpful support I received from the customer after delivery.

Black looks cool too.

UMAREX/VFC G45
This is one of Glock's latest models (GENERATION.5).

UMAREX/VFC G45 Spare Magazine
Since it's an imported product, I recommend getting it while supplies last.

・Injection valve for domestic gases
I recommend it (but be sure to use genuine O-rings).