CNC gearbox designed for M249 or PKM airsoft replicas. 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, our gearboxes have the best durability and resilience than common zinc-aluminum gearboxes. We are manufacturing these gearboxes on our precise CNC milling machines in our factory. Detail in bracket (8mm) means diameter for bushings / bearings.

Package includes: CNC Gearbox M249 / PKM (8mm) - set of screws.

We made some useful improvements into our CNC M249 / PKM gearboxes:

    Spring holders have grooves, so the springs for tapped plate and trigger switch will not jump off.
    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.
    All threads are now shaped instead of cutted for better strength.
    Both of the gearbox parts are centered by milled grooves and edges.
    Gearbox was re-designed to be lighter but stronger in the most critical parts
    Added groove for anti-reversal latch spring, so it will not jump off.
    Outer edges are now cutted off.

RetroArms gearbox has quick spring change system QSC, where you can put 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 with the spring. This is because the spring guide is not fixed in the gearbox but has will for easy removing with hex key.

CNC gearbox M249 / PKM 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 means even the inner parts. Do not use rude force during installation. Use only 1Nm tightening moment on screws, otherwise the screws will overturn in heads. 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.

!! do not use MAXX cylinder head !!

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