15 Raizen – AEG EVOLT & New Gen MP5 Inner Barrel

Description

Industry-Leading SUS304 Barrel — The “RAIZEN” Series
The RAIZEN barrel is manufactured from ultra-precision SUS304 stainless steel tubing produced using Japan’s renowned precision tube manufacturing technology.
It is one of the signature products that represents the da Vinci custom brand.

We believe you will appreciate both the beauty and performance that truly embody Made in Japan quality.

A Loose 6.15mm Bore — Ideal for Fine-Tuning Your Setup
As a basic principle, the smaller the clearance between the inner diameter of the barrel and the BB, the greater the pressure acting from behind the BB, generally resulting in higher muzzle velocity.

With a 6.15mm inner diameter, there is considerably more clearance around a 6mm BB. Depending on the setup, this can be used to intentionally reduce muzzle velocity. On the other hand, when combined with a system capable of supplying sufficient air volume, the larger bore can propel the BB without placing excessive stress on it, potentially producing excellent long-range performance.

This wide-bore configuration offers a unique tuning character that cannot be achieved with conventional tight-bore barrels.

One of the Most Complex Inner Barrel Designs Ever Made for an AEG
One point that cannot be overlooked when discussing the Next Generation MP5 and EVOLT-M4 inner barrel — hereafter referred to as the EVOLT barrel — is the extremely high level of machining difficulty involved.

In particular, the anti-rotation grooves used to position the hop-up bucking are especially demanding. While a conventional AEG barrel normally has only one such groove, the EVOLT barrel features four separate grooves, each of which requires a high degree of positional accuracy.

The tools used to machine these grooves are specialized cutting tools, and one of the challenges is that accurately verifying the resulting angular positions after machining is extremely difficult.

At da Vinci custom, we use a specialized method to measure and verify the indexing accuracy of these angles, allowing us to reproduce the required geometry as precisely as possible. This improves the installation angle accuracy of the hop-up bucking and contributes to more consistent, high-quality hop performance.

This is an exceptionally difficult machining process, and we believe very few, if any, manufacturers go to this level of effort in producing this type of barrel.

Front Groove Position Shifted Forward from the 2nd Production Lot
Due to the characteristics of the machining process, grooves positioned closer to the muzzle end can be machined with greater accuracy.

For this reason, from the second production lot onward, the front groove position has been shifted closer to the muzzle.

Precision Taper Machining for Improved Performance
As with the GUREN 2 series, the muzzle end is finished with our precision taper machining.

This tapered geometry allows air to exit the barrel more efficiently, converting the airflow into energy that helps propel the BB while also stabilizing the escaping air.

The result is improved consistency and enhanced accuracy.

RAIZEN Inspection Standards
After polishing, every RAIZEN barrel undergoes an internal diameter inspection.

Particular attention is given to ensuring that any burrs generated during machining have not affected the inner bore. This is first checked physically, then inspected once again visually by the small group of experienced craftsmen entrusted with the polishing process.

Up to this point, the inspection procedure is the same as that used for the GUREN series. However, RAIZEN is held to a stricter standard for surface roughness, and any material showing excessive surface irregularities originating from the raw material itself is carefully rejected.

The reason RAIZEN is positioned as a premium barrel is not only the higher cost of the material, but also the amount of time required for selection and inspection, as well as the quantity of material that ultimately fails to meet our standards.

For this reason, every RAIZEN barrel delivered to you is selected from only the finest pieces that pass our inspection process.

Machining patterns that do not affect performance or use — such as cutter marks or tool marks — may occasionally remain visible. These have already passed the inspection process described above and have been approved by our craftsmen, so they can be used with confidence.