Retro Arms CNC Anodized Gearboxes for HPA V2

Yes. We can build and upgrade Hi-Capas, AAP platforms, and rifles. Choose your base gun and parts, then add the appropriate tech service.

The current custom-build service states that builds are normally completed in approximately 3 to 5 days, with the team reviewing the selected parts for compatibility.

That depends on the upgrade. Simple external parts may be straightforward, but internal upgrades can require disassembly, reassembly, adjustment and testing.

If you are not comfortable working inside your airsoft gun, our team offers professional tech and custom-build services.

Orders without preorder items are typically packed the same day when placed before 4:30 p.m. Central Time. Please note that occasional delays can occur during especially busy periods or when staffing is limited.

Regular maintenance helps preserve performance and reliability. Keep the product clean, follow the manufacturer’s lubrication instructions, and properly manage batteries, gas systems, and internal components. More advanced repairs or internal servicing should be handled by an experienced airsoft technician.

Compatibility is product-specific. Check the brand, model, size, and platform named in the product description, such as Tokyo Marui Hi-Capa 4.3 or 5.1, AAP-01, Umarex/VFC Glock, or a particular AEG gearbox type.

Similar-looking parts are not always interchangeable, so contact our team with your exact model if you are unsure.

Not every upgrade increases FPS. Some parts are designed primarily for reliability, cycling speed, weight reduction, or gas efficiency. When a product has a tested FPS claim, it should be stated in the listing.