[SPARK] Hisei Kai High-Precision Inner Barrel, 6.05mm Bore, 250mm for GHK

The ultimate inner barrel that delivers performance that satisfies SPARK custom engineers.

To achieve stable trajectory and accuracy, the craftsmen at da Vinci, the manufacturer of the custom barrels Guren/Raizen, have combined their cutting-edge metalworking skills with the SPARK concept to develop the 100% Japanese-made, high-quality, ultra-precise inner barrel, Hirei®. Further refinements have been made in various areas to create the ultimate, top-of-the-line inner barrel, Hirei® Kai.

The material used is the highest quality domestically produced stainless steel, produced by cold forging, and is also manufactured using precision machining using domestically produced high-precision CNC machines.

To ensure a stable hop-up effect, the hop-up window has been carefully shaped and polished, and the end of the barrel has an ultra-long taper of 20 mm, designed to create a layer of air that envelops the BB bullets!
The extraordinarily long taper streamlines the air layer surrounding the BB bullets, and in combination with the tight 6.05 mm diameter, it achieves improved initial velocity, accuracy, and distance.


To prevent possible collisions with the loading nozzle, no expense has been spared, with expertly crafted tapered processing also being applied to the inner walls.
This is a high-quality, domestically produced product that incorporates the best of Japanese technology and is recommended for those seeking a higher level of accuracy.

"Hiei" is a registered trademark of SPARK, an inner barrel for airsoft guns.

*Due to the special taper, the inner barrel cannot be cut.
*Power will vary depending on the assembly. Please be sure to adjust the power yourself, especially with heavy bullets, carefully to ensure that the legal limit (less than 0.989 J / 35°C) is not exceeded.

[Compatible models]

GHK CO2 GBB AR series 2022~ lot

We have confirmed compatibility with V2 and V3 units.
For other lots, please check the fixing groove position in the product image.

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Installation guidelines

• Mk18 → 250mm can be used as is

• M4A1 14.5 inch → 250mm + GHK barrel spacer (sold separately) required

[ Features of Hirei® Kai ]

• Super polished HOP window

A stable hop-up is important for a stable trajectory.

The interior walls, including the area around the HOP window, are thoroughly polished by craftsmen to eliminate any uncertainties that may affect the BB bullets.

The HOP window is subjected to a "round cutting process" which is extremely difficult to process, which allows the HOP packing to move smoothly and maximizes its performance.

• 20 mm ultra-long taper

Due to its extremely hard nature, cold-forged stainless steel is extremely difficult to machine, requiring highly precise CNC machines, skilled craftsmen to select cutting teeth, and meticulous machining programming. The exceptionally long taper of 20 mm suppresses sudden changes in resistance around the barrel exit and increases in turbulence coefficient, eliminating the negative effects on accuracy. This maximizes the gun's inherent accuracy.

• Proudly made in Japan

It is easy to describe the precise round cutting of the HOP window, the polishing of the inner surface of the barrel, and the long taper processing of the muzzle side, but creating an ultra-precise inner barrel using cold-forged stainless steel, which is difficult to process, requires a high level of technical skill.

"Hirei® Kai" is a MADE IN JAPAN product that Japan is proud of around the world.

[Notes]

• This product is intended for ages 18 and over, and cannot be purchased by anyone under the age of 18.

• Even if the product is new, there may be scratches on the product itself or its accessories from the time of shipping. Even if the product is the same, there may be differences in color between individual products, but these are all within the product specifications.

• The external specifications and accessory configuration may change without notice. In addition, the original box may be modified or repackaged if the packaging is missing or damaged.
• When installing, please be careful not to violate the legal power by using a muzzle velocity meter or similar device.
• Processing and adjustment may be required for installation.
• The product description does not guarantee improved performance.