KWA RM4 ERG M120 Main Spring for RM4 AEG Recoil Series Rifles

Restore factory performance to your KWA RM4 ERG or upgrade a worn recoil rifle spring with the genuine KWA RM4 ERG M120 Main Spring. Manufactured by KWA as an OEM replacement part, this spring is engineered specifically for the company's AEG3 Recoil (ERG) gearbox, delivering the consistent compression, reliable cycling, and dependable performance that KWA recoil rifles are known for. :contentReference[oaicite:0]{index=0}

Unlike standard AEG springs, the RM4 ERG utilizes a proprietary short spring designed to work with KWA's electric recoil system. Installing the correct OEM spring helps maintain proper recoil operation while restoring muzzle velocity lost through normal wear. Whether you're performing preventative maintenance or rebuilding your rifle after extensive use, this factory replacement ensures the correct fit without modification. :contentReference[oaicite:1]{index=1}

Designed for compatibility with KWA RM4 and other AEG3 Recoil System platforms, this M120 spring is the same style found in many factory-configured RM4 rifles. As with any airsoft spring upgrade or replacement, final FPS will vary depending on barrel length, air seal, compression components, and overall gearbox condition.

Features

• Official KWA OEM replacement part
• M120-rated main spring for KWA AEG3 Recoil (ERG) gearboxes
• Restores factory performance and cycling
• Designed specifically for KWA's proprietary recoil system
• Precision wound hardened spring steel construction
• Ideal replacement for worn or fatigued factory springs
• Helps maintain consistent compression and air seal performance
• Drop-in replacement for compatible KWA RM4 AEG Recoil rifles
• Perfect for routine maintenance or complete gearbox rebuilds

Specifications

Length: 152mm
Weight: 14g
Material: Hardened spring steel
Spring Rating: M120
Compatibility: KWA RM4 / AEG3 Electric Recoil (ERG) rifles including RM4A1, PTS RM4 Scout, Ronin T10, and compatible AEG3 recoil models
Manufacturer: KWA