All-Round Build Kit for AK AEG (V3 Gearbox)

The All-Round Build Kit for AK is our complete upgrade for AK AEGs with a standard V3 gearbox – AK47, AK74, AKM and most clones from e.g. LCT, Cyma, Arcturus and Double Bell. The kit brings together the parts that genuinely move performance in a standard AEG: gear set, motor, piston, piston head, cylinder head, spring guide and spring. The parts are chosen to work together as one setup, not just as individual parts. The result is an AK with fast semi-auto response, a rate of fire of around 21 rounds per second on an 11.1 V battery with the brushed motor, and a gearbox built to last through many game days.

The setup is the same as in our All-Round kit for M4 – gearing, motor and spring force are matched to the way most people play, mainly semi and short bursts. The difference lies in the parts specific to the V3 gearbox: cylinder head and spring guide. The AK uses the same long-shaft motor type as the M4, so the motor choice is the same. You can fit the kit yourself, or let our workshop assemble, shim and test it.

A well-matched setup for the V3 gearbox

The parts are chosen to complement each other and fit a standard AK V3 gearbox:

• Gear set in the 16:1 class: A mid ratio that gives faster cycling than the standard 18:1 without needing the high-speed modifications that 12:1 and 13:1 typically do. Gear sets in V2 and V3 gearboxes are the same, so you get exactly the same gearing as in the M4 kit.
• Piston with 14-tooth metal rack: The body is PA66 polymer, and the tooth rack is metal all the way. The 14th tooth is matched to the sector gear's engagement (AOE), so the cycle becomes more consistent. An all-plastic piston is the typical weak point in a standard gearbox when spring force goes up.
• V3 cylinder head for AK with two O-rings: The cylinder head is made for the AK version of the V3 gearbox and has a flat face that matches the kit's flat aluminium piston head. The two O-rings give a tight seal to the cylinder, so compression is not lost.
• Brushed or brushless motor: The standard variant uses a long-shaft, high-torque brushed motor matched to the gearing. The brushless variant uses our own HT Brushless 39K, which can be set to 31,000 or 39,000 RPM. There are no brushes to wear, and efficiency is higher. If your AK doesn't already have a MOSFET/ETU, you can add one made for the V3 gearbox: the E-Shooter Kestrel V3 SE or Jefftron Leviathan V3 with its own trigger.
• Free choice of spring from M100 to M130: You choose the spring based on the site you play at. The whole build is matched to this range, and the V3 spring guide with thrust bearing makes it easy to change spring later.

Maintenance and safety

• Fitting requires disassembly of the gearbox, shimming and correct lubrication. The V3 gearbox sits inside the AK receiver and takes more steps to remove than in an M4 – if you haven't done it before, we recommend having it fitted in our workshop
• Always measure velocity with a chronograph after fitting, and stay within the site's limits for your type of replica
• Use an 11.1 V LiPo battery with a suitable discharge rating, and always charge with a balance charger in a LiPo safety bag
• Clean the barrel and hop-up regularly, and inspect the gearbox after a season with many game days
• Always wear approved eye protection during play and testing