SHS M120 Main Spring - The DMR Standard for Long-Range Precision

When you are building a dedicated marksman platform - the SHS M120 is the definitive choice for reaching those high-power limits allowed at UK outdoor sites. This isn't just a "stronger" spring - it is a precision-engineered component designed to provide the consistent velocity required for accurate - long-distance shots. If you are looking to outrange standard AEGs and hold your own in the open fields of a British woodland site - the M120 is your foundation for success.

Key Features and Performance

• High-Tensile Piano Wire Construction - Manufactured from premium steel to ensure the spring resists "shrinking" or losing its power rating over time.
• Non-Linear Pitch Design - Features uneven coil spacing to reduce stress on your motor and gears during the initial cycle - providing a smoother internal action.
• Zinc-Plated Finish - A smooth - corrosion-resistant coating that ensures the spring glides inside the piston without snagging or creating metallic debris.
• Consistent Compression - Engineered for a uniform return rate - which is vital for maintaining a steady FPS and tight shot groupings.
• Universal AEG Fitment - Designed to work perfectly with all standard Version 2 - 3 - and 6 gearboxes - including those with quick-change spring guides.

The "Pro" Take

The SHS M120 is a staple in the UK tech community for one reason: reliability. While some "boutique" springs can be inconsistent - the SHS M120 hits its marks time and time again. For a pro-level DMR build - consistency is more important than raw power - and this spring delivers a very narrow FPS deviation. When paired with a high-quality full-metal rack piston and a high-torque motor - it creates a crisp - authoritative firing cycle that lets the opposition know exactly what they are up against.

UK Spec and Site Performance

In the UK - the M120 is a "heavy hitter." In a standard AEG with a good air seal - this spring will almost certainly push you over the 350 FPS (1.13J) limit - making it unsuitable for "Full Auto" use at most sites. However - it is the perfect "Sweet Spot" spring for UK DMR builds.

Most UK sites allow semi-locked DMRs to shoot up to 400 or 450 FPS (approx. 1.88J). An M120 - combined with a high-quality 400mm+ inner barrel and a perfect air seal - typically lands right in that 400-420 FPS bracket. This is ideal for large - sprawling sites like "The Mall" or "Frontline" - where you need the extra range to lock down corridors or clear treelines. Because of the higher tension - we strongly recommend using 0.30g to 0.40g BBs to ensure your shots aren't caught by the crosswinds common in the British countryside.

Friendly FAQ

Will this make my gun a DMR?
Installing the spring is the first step! To be site-legal as a DMR in the UK - you will also need to "semi-lock" your gearbox (disable full-auto) and adhere to the specific minimum engagement distances (MED) of your local site.

What battery should I use with an M120?
We highly recommend a high-discharge 11.1v LiPo battery. The extra voltage is necessary to pull back the stiffer M120 coil efficiently without causing trigger lag.

Do I need to upgrade my internals?
Yes - we suggest ensuring you have a metal-toothed piston and a high-torque motor. An M120 puts significantly more strain on your gears and motor than a standard M90 or M100 spring.

Is this legal for CQB?
Likely not. Most UK CQB sites have a strict 350 FPS limit. An M120 will almost certainly exceed this - so keep this spring for your outdoor woodland or long-range setups!