The 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 gearbox and piston while maintaining reliable power output.
Perfect for high-torque, DMR, or precision builds that demand consistent FPS and durability.
Features
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Made from high-grade silicon-chromium (SiCr) alloy steel for durability and elasticity
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Progressive winding for smoother compression and less mechanical stress
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Designed specifically for SR25 and extended gearbox platforms
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Provides stable FPS output and consistent performance
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Ideal for DMR and high-power AEG builds
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Resistant to deformation and spring fatigue even under heavy use
Specifications
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Material: Silicon-Chromium (SiCr) Spring Steel
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Spring Rating: M140 (approx. 450–480 FPS depending on setup)
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Type: Progressive Winding
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Compatibility: SR25 / Extended gearbox platforms
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Brand: RetroArms
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Origin: Made in Czech Republic
What's Included
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1x RetroArms SR25 Spring SiCr with Progressive Winding M140
Important Notes
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Installation should be performed by experienced airsoft technicians.
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Ensure proper gearbox reinforcement when using high-rated springs.
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FPS output may vary depending on barrel length, cylinder volume, and air seal quality.
Disclaimer
⚠️ This product is an upgrade part intended for toys only. Not for real firearms.
