ACM M140 AEG Spring (SP140)

Boost your muzzle velocity and gain a distinct competitive edge during long-range outdoor games with the ACM M140 AEG Spring (SP140)! Engineered as a high-power drop-in upgrade for Airsoft Electric Guns (AEGs), this main drive spring supplies the force required to punch through light foliage and maintain flat, high-velocity trajectories at long engagement distances.

High-Tensile Alloy Steel & Non-Linear Winding Forged from premium heat-treated alloy steel, the ACM M140 spring is specially tempered to maintain consistent tension without sagging, shortening, or suffering spring fatigue after thousands of high-stress cycles. It features a non-linear (variable pitch) coil layout that distributes spring spacing unevenly along the steel body. This design allows the motor and gear set to overcome lower resistance during the initial stage of the piston pullback, significantly decreasing battery drain and startup torque strain on your motor. Once fully drawn back, the tightly wound coils compress to release explosive, repeatable forward thrust against the piston assembly.

High-Velocity Field Performance & Ground-Flat Ends When installed in an AEG build featuring efficient air seal components and tight-bore inner barrels, an M140 rating generates approximately 440 to 470 FPS (tested using standard 0.20g BBs). This higher energy output makes it an ideal choice for outdoor field rifles, heavy-BB setups (.28g–.36g), and entry-level DMR builds. Both ends of the spring are ground flat to sit completely flush against bearing spring guides and piston heads, preventing spring binding, rotational twisting, and uneven lateral pressure inside the gearbox cylinder.

Universal Gearbox Fitment Manufactured to standard airsoft main spring dimensions, the ACM M140 is universally compatible with standard Version 2, Version 3, Version 6, and quick-change spring gearbox shells. Note: Due to the increased tension of an M140 spring, it is recommended to pair this item with reinforced metal gearbox shells, high-torque motors, steel gear sets, and steel-tooth pistons. Power up your build with the long-lasting performance and value of the ACM M140 AEG Spring (SP140)!