RetroArms CNC Split Gearbox V2 with hop-up chamber (8mm) - QSC

CNC split gearbox V2 designed for airsoft replicas AR15 (M4), M16 and other ones with V2 gearbox. This gearbox is manufactured from one solid block of aircraft aluminum (Dural) EN AW 7075 T651, which has higher strength (590MPa), than common construction steel (390MPa). Because of used material, gearboxes have the better durability and resilience than common zinc-aluminum gearboxes. Gearboxes are manufactured on precise CNC milling machines.

Split gearbox means, that this gearbox is designed as a three part, Upper, Lower and a hop up chamber. There is a special compartment milled into an upper part, in which the hop up chamber is mounted. Having a split gearbox has many advantages. For example much more easy installation of the inner parts into the gearbox. During the air system tuning, there is no need of removing whole gearbox from your gun, only upper part can be removed, because it‘s mounted on one receiver pin. However, the biggest advantage of a split gear box with an integrated Hop Up chamber is the absolute alignment of the gearbox with the Hop Up chamber, and the Hop Up chamber does not bounce when shooting because it is attached to the gearbox. In addition, the gearbox with an integrated Hop Up chamber partially compensates for the slightly curved bodies of the AR15(M4), where performance is a problem due to misalignment. For very crooked AR15 bodies, we recommend using a split gearbox, but without an integrated Hop Up chamber, so that the chamber is not pryed.

The Hop Up chamber is regulated by a rotary wheel with a click, which means that even when shooting, the Hop Up setting stays as it is set. The Hop Up chamber is equipped with an original collet nut that prevents the inner barrel from loosening during firing. Because of the collet nut, the barrel lock is turned by 180°, because otherwise the Hop Up chamber would not fit into the outer barrel. Due to the groove in the collet nut, the nut deforms and tightly clamps the inner barrel into the chamber so that the inner barrel cannot move during firing.

The recommended length of the nozzle for the integrated Hop Up chamber is 21,3 mm. Compared to the standard size of 21,4 mm for AR15 (M4) weapons, this is due to the integrated Hop Up chamber, which does not bounce during firing. However, the length of the nozzle can be affected by other factors, in particular the angle of inclination of the feeder arm or the different length of the collar of the Hop Up rubber, when in rare cases it may be necessary to use a nozzle with a different length.

Package includes: CNC split gearbox V2 with integrated hop-up chamber (8mm), pressure lever, adjustment wheel, spring, plastic pin, collet nut, screw set, and QSC spring guide.

Some useful improvements:

• Spring holders have grooves, so the springs for tapped plate and trigger switch will not fell off.
• Added groove for safety lever, so it will hold during installation.
• Added groove for trigger spring, for better fitting.
• AOE control hole.
• Sockets for bushings/bearings have smaller diameter about -0,02mm (7,98mm), for non-overturning the bushings during installation. The socket edges are cutted down for better installation.
• We enhanced grooves for wiring for 1mm, you can now use wirings with 2,5mm diameter.
• Added protecting edge for wiring against the motor.
• All threads are now shaped instead of cutted for better strength.
• Both of the gearbox parts are centered by milled grooves and edges.
• Added hole for releasing anti-reverse latch.
• For better durability, we added more material around cylinder head part of the gearbox, this was the most critical part and we added 100% more material where is huge radius.
• Added groove for anti-reversal latch spring, so it will not jump off.
• Outer edges are now cutted off.
• You can find what type of sockets gearbox have on the outside part of the gearbox (8mm or 9mm).

RetroArms gearbox has quick spring change system QSC, where you can take out whole spring guide with hex key and change the spring without need of opening the gearbox. In this solution, you need to secure spring guide with screw, commonly with AR 15 (M4) replicas, it is by stock screw. In situations where you have folding stocks or no stock at all, you have to secure the spring guide with QSC screw. Otherwise there could be situation, where the spring guide will stuck into the spring.

Space for trigger switch is designed for compatibility with trigger switches, trigger units from common manufacturers for example: Gate, etc.

CNC gearbox V2 has protective anodizing, even when it is problematic to anodize aluminum EN AW 7075 T651 (Dural), because of its high strength and hardness. If we did not anodize products from this material, there is huge risk of corrosion (huge gray spots with rotten look).

CNC gearbox can be installed only in airsoft replicas with Tokyo Marui compatible standard. That also means the inner parts as well. Do not use brute force during installation. Use the tightening torque of 1Nm only on screws, otherwise the screwdriver/key damages the shaping in the head of the screw. There is no need of tightening screws with rude force, if you want to be sure that screws will sit perfectly, use thread glue or thread color.

You can use any spring of your choice in our CNC gearbox, but be aware that stronger springs will result in lower durability.

!! not compatible with MAXX cylinder heads !!

Installation of the inner parts and gearbox requires professional knowledge, experience and skills. There are a lot of airsoft manufacturers on the market and every one of them create their own dimensions, there are no standards like engineering ISO in airsoft. This is the main problem with a lot of inner and outer parts from different manufacturers which can be same product, but with different dimensions. We recommend using only parts from manufacturers with Tokyo Marui compatible mark, where should not be a problem with compatibility with our CNC gearbox.