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ACM M120 AEG Spring (SP120)
Boost your airsoft rifle’s power and effective range with the ACM M120 AEG Spring (SP120). Designed as a cost-effective performance upgrade, this steel main spring delivers an estimated output of 380 to 420 FPS (with 0.20g BBs, depending on barrel length and compression seal). Built with a non-linear (irregular pitch) coil structure, it reduces strain on your motor and gears during compression while maximizing terminal velocity upon release. Compatible with standard Version 2 through Version 7 AEG gearboxes.
Achieving the ideal muzzle velocity for outdoor field engagement requires a reliable main spring that delivers consistent compression shot after shot. The ACM M120 AEG Spring (SP120) provides a high-value, budget-friendly power upgrade for airsoft players looking to increase their rifle's FPS and effective range without overspending on brand-name internals.
Non-Linear Coil Design for Mechanical Efficiency
Unlike traditional uniform springs, this M120 spring features a non-linear (irregular pitch) winding pattern. The uneven coil spacing allows for an easier initial compression stroke, significantly reducing initial load strain on your electric motor, bevel gear, and piston teeth during the cycle. Once fully compressed, it releases maximum stored kinetic energy to drive the piston forward with consistent force.
Target Velocity & Universal Gearbox Fitment
Rated at M120/SP120 (approx. 120 meters per second), this spring typically produces 380 – 420 FPS on standard carbine-length setups using 0.20g BBs. It features standard outer and inner diameter dimensions, making it a drop-in replacement across virtually all standard Automatic Electric Gun (AEG) gearboxes—including V2 (M4/MP5), V3 (AK/G36), V6 (P90), and V7 (M14) platforms.
Key Features & Technical Benefits:
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380–420 FPS Power Output: Ideal for outdoor skirmish fields and long-range engagement roles.
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Non-Linear / Irregular Pitch Coils: Minimizes initial motor draw and gearbox stress during compression.
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High-Tensile Steel Construction: Resists spring fatigue and maintains rating over thousands of cycles.
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Universal AEG Compatibility: Fits standard V2, V3, V6, and V7 gearbox spring guides and pistons.
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Cost-Effective Upgrade: High performance-to-cost ratio for custom tech builds and FPS adjustments.
Usage & Tech Tips
Installing an M120 spring increases mechanical resistance inside your gearbox. It is highly recommended to pair this spring with a full steel-tooth piston, a metal bearing spring guide, and a high-torque motor to ensure long-term durability. Ensure your compression components (piston head O-ring, cylinder head, nozzle, and hop-up bucking) have an airtight seal to achieve maximum, consistent FPS output. Always check your local airsoft field's FPS velocity limits before installing high-power springs.
| SKU | 614474 |
|---|---|
| Brand | Double Bell |
| Weapon Category | Parts |
| FPS | 301 - 400 |
| Spring Type | AEG |
Our courier partners deliver from Monday to Friday, excluding Bank Holidays. We will attempt to dispatch all packages within 24 hours, although at peak times this may take slightly longer. Orders with products with two-tone service or Defence Check may take longer to dispatch.
Once the order is dispatched you will get an email with the tracking number and which courier partner it’s going to be delivered via. Any missing/incorrect items need to be reported with 48hrs of signed delivery.
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Faulty Product?! Unfortunately that is part of life but be rest assured we are here to help! Contact one of our friendly staff via phone or email. Stating what the problem is, if we can resolve the problem via phone or email great if not then they will advise how to send it back and what details we require.
The gun will be sprayed 51% in a bright/primary color (we do only blue, green and red currently). The process of two toning currently runs at 2 working days depending on Drying Time, which is effected by Ambient Temperature and Weather. and currently no express delivery is available for this even if you select it at checkout.