High-Speed M100 Build Kit for M4 AEG (V2 Gearbox) – Semi

The High-Speed M100 kit is for you if you want an M4 with a high rate of fire but still want to shoot accurately in semi. The kit is based on a 12:1 gear set, a low spring force in the M110–M120 class and a short 250 mm inner barrel, so the piston has time to cycle fully, even at high revs.

High-speed builds are more demanding than a normal upgrade. When the gearing gets shorter, the anti-reversal latch, bearings and piston must be able to withstand the faster cycles, and the barrel must be short enough for the air volume to match the spring. That is why those parts are included in the kit. You can fit the kit yourself, or let our workshop assemble, shim and test it. When we fit it, we chronograph the velocity and record m/s and BB weight, so the gun stays within the site's limits.

Short gearing, short barrel and parts that withstand high speed

• 12:1 CNC gear set: A shorter ratio than the standard 18:1 gives markedly more rounds per second. It requires high-speed modifications such as AOE and sector gear engagement, which the workshop takes care of when fitting.
• CNC steel anti-reversal latch: At high rates of fire the latch is loaded harder than in a standard gearbox. A CNC-machined hardened steel latch for V2 is one of the parts that most often saves a high-speed build from breaking.
• Ceramic 8 mm bearings: Lower friction than standard bushings, so the motor uses less current to drive the gears – important when the gears turn fast.
• 250 mm inner barrel: A short barrel suits the low spring force and smaller air volume of a high-speed build. A barrel that is too long causes loss of velocity and an unstable trajectory.
• Choice of M110 or M120 spring: You choose the spring based on the site. Both are matched to the gearing, so the kit can stay within the full-auto limit.

Maintenance and safety

• Fitting requires disassembly of the gearbox, shimming and correct lubrication. 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