RetroArms SR25 Spring SiCr with Progressive Winding — M140 Gearboxes and FPS consistency

and FPS consistency

Stock Type: Adjustable stock with battery storage

1x RetroArms Selector Plate V2 (AR15)

and precision tuning for your AEG build

this grip enhances stability and control while maintaining a lightweight and rugged design—ideal for training

RetroArms SR25 Spring SiCr with Progressive Winding — M140 Gearboxes and FPS consistencyThe RetroArms SR25 Spring SiCr with Progressive Winding M140 is a high performance main spring designed for SR25 and extended gearbox builds that require powerful and consistent compression. Manufactured from silicon chromium (SiCr) alloy steel, this spring offers superior resilience, reduced fatigue, and long term stability compared to standard carbon steel springs. The progressive winding design ensures smoother compression, reducing stress on the