Now let's think about how to actually realize the ideal structure.

By providing a contact part below the pepperball holding position, the contact point is limited and the structure is such that the pepperball is stably held.

The contact portion is projected toward the center of the barrel to hold the bullet at the center of the barrel.

The structure is such that the Airsoft BBs are held by three-point support, which is a stable support method for spheres.

● Prototype the ideal structure

So, I've been thinking about it, but after all, it's just a "hypothesis." So you have to "experiment" to see if it works. For "experiment", it is necessary to "prototype". Let's think about each part.

○ pepperball holder

In order to realize the ideal pepperball holding part, consider providing a contact part with sufficient height directly below.

Assuming that the normal barrel of the Tokyo Marui electric gun is used, the nominal inner diameter is 6.08 mm. For pepperballs, assume a nominal diameter of 5.96mm ± 10μm. Then, it is sufficient to add a contact part with a height of about 60 μm (0.06 mm).

The first thing I tried was cellophane tape (thickness 55 μm), and the thickness itself was a good feeling. However, it was not durable at all.

The next thing I thought about was Teflon coating tape (thickness 100 μm). I pasted it. It seemed to be improved, but it was still a questionable result, probably because the thickness was not appropriate. It also lacks durability. Hundreds of shots felt like they could withstand.

The next thing I tried was a stainless sheet tape (thickness 50 μm). It had an adhesive, but the adhesive strength was too weak, so I burned the adhesive (thickness 45 μm) and fixed it with an anaerobic adhesive. The result was good. However, I am worried about when it will come off. The durability was like, "Can you withstand a thousand shots?" After that, it actually came off.

That's why, in addition, we made a "prototype" by using the contact part as a separate part. The following points were taken into consideration when determining the shape of the parts at this time.

Contact parts do not fall into the barrel

Large adhesive area

Narrow contact area

In the end, we used a jig to bond an iron plate with a thickness of 0.2 mm to a bent part (center tip) to the normal barrel of an electric gun with additional grooves and adhesive surfaces. It has a structure that holds BB bullets in contact with the curved surface part where the plate is bent. (See figure)

■ Structure of prototype

○ Hop-up protrusion

With reference to the hop lever of Tokyo Marui electric hand gun etc., we made a part (2-point hop part) instead of the cushion tube with a 3mm cutout in the center.

Also, we made V-hop type parts (V-hop parts) by processing the hop-up protrusions. An arc shape is cut out instead of a V groove so that there is a gap between the two points on the left and right where air leaks.

★ Ideal pepperball holder

It has been said that the hop-up system with left and right two-point contact hop-up protrusions called "2-point hop" and "V hop" has been stable for some time. Why is this?

First of all, in the hop-up system with one point contact on the upper side, it is possible that the pepperball bullet will rotate with respect to the vertical axis (see the figure). Rotation in this direction only has a negative effect when trying to stabilize the hop-up rotation or hop-up central axis.

On the other hand, it can be considered that the hop-up system with two left and right points does not rotate with respect to the vertical axis. Furthermore, it is presumed that it is stable because it is a three-point support, which is a stable support method for spheres.

A sphere with gravitational force can be held stably by restraining 3 points. Think of it as a stable three-legged table.

When considering a hop-up system, 3 points are decided, and if which point slips is decided, the hop-up central axis is decided. If the positions of the three points are stable, the hop-up central axis will be stable.

In the case of a hop-up protrusion that contacts two points on the left and right, rotation starts around the line connecting these two points (see the figure). If the position of the lower contact point fluctuates due to the distortion of the Airsoft BB, the line itself connecting the two points on the left and right of the hop-up protrusion will be forcibly shifted, and it will rotate around the shifted axis. Begins (see figure). In other words, the hop-up central axis is forced to change. Furthermore, as the BB bullet rotates, the contact point may move from side to side. If this happens, the hop-up central axis will further vary.

For this situation, the position of the lower contact point can be limited by providing a contact part with a sufficient height at the bottom. By doing so, the inclination and variation of the hop-up central axis can be suppressed to a small level.

Furthermore, by providing a contact part, it is possible to have a structure that holds pepperballs at the center of the barrel. In addition, since the hop-up protrusion is less pressed, the range of possibility of variation in bullet ejection resistance can be reduced.

■ In the case of one-point contact on the upper side

■ In case of left and right two-point contact

■ In the case of a distorted Airsoft BB with two left and right contact

★ Experimental parts abbreviation

Parts used Abbreviation

Normal barrel N

Center tip barrel R

2-point hop part 2

V hop part V

★ Experimental combination conditions

symbol

Normal barrel + cushion tube + normal protrusion N

Normal barrel + 2-point hop parts + normal protrusion N-2

Normal barrel + 2-point hop parts + V hop parts N-2-V

Center tip barrel + cushion tube + normal protrusion R

Center tip barrel + 2-point hop parts + normal protrusion R-2

Center tip barrel + 2-point hop parts + V hop parts R-2-V

For each combination, 10 grouping / 20m was performed 3 times.

★ Experimental conditions

Tokyo Marui P90TR fixed on a craft stand

Hop-up: Long-distance settings for games

Initial velocity: 81-82 m / s

pepperball bullet: Excel semi-bio 0.2g

Barrel length: 247 mm

Cylinder: P90TR standard acceleration cylinder

It is assumed that there is no individual difference in the mechanical box, chamber parts, and normal barrel.

Outdoors, breeze

● Experimental results

An experiment was conducted using a center chip type prototype. At the same time, we also experimented with a combination of two-point hop parts and V-hop parts. The experimental results are shown below.

Combination Elasticity [mm] 10 shots Semi-auto / 20m

1st 2nd 3rd Average

N 310 207 200 239

N-2 236 200 310 249

N-2-V 225 165 190 193

R 163 163 186 171

R-2 205 220 132 186

R-2-V 152 132 162 149

● Summary

When the experimental results were calculated according to the statistical method, the result was that the center tip barrel was "improved with a probability of 95% or more" compared to the normal barrel. There are some questions that remain, but I think it is a matter of disturbance and delicate adjustment.

While many custom barrels have unclear effects, I think that "stable and clear results" have been obtained.

We thought that this custom barrel was not at a level that we could make by ourselves, so we commercialized it so that everyone could experience this effect. We are confident that many airsoft enthusiasts will be satisfied. Please try!

In addition, we have applied for a "patent" in connection with this research report. Therefore, please refrain from manufacturing and selling custom barrel products that use the contents described here without permission.