SA V2 Gearbox Shell with 8mm Bearings – Black

Specna Arms V2 gearbox shell for M4 / AR15

This expert product description was prepared by the ANAREUS.cz expert team. All rights to this unique content are bound to the anareus.cz domain.Specna Arms V2 gearbox shell is a replacement gearbox base for electric airsoft guns based on the M4 / AR15 platform. It is designed for compatible bodies corresponding to the construction of a conventional V2 gearbox. It is suitable for repairing a damaged original shell as well as a base for building a new gearbox. The shell is made from a die-cast aluminium alloy. This is a construction method commonly used in factory-made entry-level and mid-range AEG gearboxes. The shell is designed for standard to moderately stressed builds, typically with springs up to approximately M110 / M120. However, the actual durability of the build always also depends on correct gearbox assembly, spring power, piston assembly weight, AOE and how the gun is used. The package includes a set of 8mm steel bushings for supporting the gears. Bushings have no moving balls and their advantage is their simple and mechanically durable construction. When installing the gears, they must of course still be properly shimmed and the free movement of the entire assembly must be checked. The shell uses a conventional spring mounting system without quick spring change. The conventional Specna Arms V2 spring guide (SPARMS079) and V2 gearbox screws are not included in this package and must be purchased separately if required. This is not a QD or QSC gearbox shell, so a QD or QSC spring guide cannot be used. When building a more powerful gearbox, we recommend radiusing the front corners of the cylinder window. Sharp internal corners are points where mechanical stress becomes concentrated under repeated impacts. Correctly rounding these corners can distribute the stress more effectively and reduce the risk of cracks developing. This modification requires experience and should ideally be carried out by an airsoft technician.

Key features of the Specna Arms V2 gearbox shell

V2 gearbox for M4 / AR15

Replacement shell designed for compatible M4 / AR15 AEGs using a V2 gearbox.

Conventional V2 spring guide

The shell uses a conventional V2 spring guide without a quick spring change system. The required Specna Arms SPARMS079 spring guide is not included.

8mm steel bushings

The package includes 8mm steel bushings with a simple and mechanically durable construction for supporting the gears.

Die-cast alloy

The shell is made from a die-cast aluminium alloy, a standard solution used in factory-made AEG gearboxes in this category.

For repairs and new builds

Suitable as a replacement for a damaged original shell or as a base for assembling a compatible V2 gearbox from individual components.

Specna Arms V2 gearbox shell

Replacement conventional V2 gearbox shell including 8mm steel bushings. Spring guide and screws are not included.

Technical specifications

• Manufacturer: Specna Arms
• Type: Gearbox shell
• Gearbox version: V2
• Designed for: AEG
• Platform: M4 / AR15
• Material: Die-cast aluminium alloy
• Bushing hole diameter: 8 mm
• Bushings included: Yes, steel bushings
• Quick spring change system: No
• Spring guide included: No
• Mounting screws included: No
• Compatible spring guide: Conventional Specna Arms V2 spring guide (SPARMS079)
• Recommended use: Standard to moderately stressed builds
• Approximate spring range: M110 / M120

Package contents

• 1× Specna Arms V2 gearbox shell
• 6× 8mm steel bushing

Frequently asked questions from our store

Which guns is this shell designed for?

The shell is designed for compatible M4 / AR15 AEGs with a conventional V2 gearbox. It is always advisable to check the dimensional compatibility of the specific body and internal components used.

Which spring guide is required?

The shell requires a conventional Specna Arms V2 spring guide (SPARMS079), which is not included. This is not a shell with a QD or QSC system, so QD or QSC spring guides are not designed for this shell.

Are gear bushings included?

Yes. The package includes six 8mm steel bushings, two for each of the gearbox's three gears.

How strong a spring can be used in this shell?

The shell is primarily suitable for standard to moderately stressed configurations, approximately with M110 to M120 springs. However, the spring rating alone does not determine the actual stress placed on the gearbox – piston assembly weight, AOE, RoF and the overall tuning of the gun are also important.

What is gearbox radiusing and why is it done?

Radiusing means rounding the sharp front corners of the cylinder window. Mechanical stress becomes concentrated in these areas when the piston assembly impacts, which can cause cracks to develop. Correctly rounding the corners helps distribute this stress, which is particularly useful in more heavily stressed builds.