Maddog Replacement Airsoft AEG Upgrade Springs

Replace a worn spring or tune a compatible AEG gearbox with the spring rating that fits your build. Maddog Airsoft AEG Upgrade Springs are designed for maintenance, repair, and custom tuning applications in many standard Airsoft Electric Guns.

Each spring features a progressive, non-linear variable-pitch design with visibly tighter coil spacing toward one end and wider spacing toward the other. Multiple strength ratings allow experienced builders and airsoft technicians to select an appropriate spring for the gearbox, supporting components, intended use, and local field requirements.

Spring rating alone does not guarantee a specific FPS, range, rate of fire, or energy level. Final performance depends on the complete AEG configuration, including compression efficiency, barrel setup, drivetrain components, BB weight, and quality of installation.

Verify compatibility. Match the complete build. Always chronograph after installation.

Maddog AEG Upgrade Spring Features

• Replacement and tuning spring for compatible Airsoft Electric Guns
• Progressive, non-linear variable-pitch coil design
• Tighter coil spacing on one end and wider spacing toward the other
• Available in multiple spring-strength ratings
• Suitable for AEG maintenance, repair, and custom gearbox builds
• Can replace a worn, damaged, or fatigued factory spring
• Compatible with many standard AEG gearbox configurations
• Includes one Maddog AEG upgrade spring
• Includes a Maddog spring guide card when available
• Professional installation is recommended
• Chronograph testing is required after installation

Progressive Non-Linear Coil Design

Maddog AEG Upgrade Springs use a variable-pitch coil layout. The spacing between the coils is not uniform across the full length of the spring. One end has more closely spaced coils, while the opposite portion has wider coil spacing.

This construction is commonly described as a progressive or non-linear spring design. The description refers to the spring's physical coil arrangement and should not be interpreted as a guarantee of any particular performance result.

Choose the Right Spring for Your AEG Build

A higher spring number generally represents a stronger spring category. However, M-ratings are not guaranteed FPS measurements and are not perfectly standardized across every spring manufacturer or AEG platform.

Select the desired spring rating from the available product options. Common Maddog spring ratings may include:

• M100
• M105
• M110
• M115
• M120
• M125
• M130
• M135
• M140
• M145
• M150

Not every rating may be available at all times. Refer to the current product selector for available inventory.

This guide provides general selection context only. It does not guarantee FPS, energy, range, compatibility, or field compliance.

Why Replace an AEG Spring?

Replace a Worn or Damaged Spring

An AEG spring may weaken, deform, or become damaged through normal use, extended compression, improper installation, or general gearbox wear. Replacing the spring can be part of a complete maintenance or repair service.

Tune a Custom Gearbox

Experienced builders may use different spring ratings when configuring an AEG for a particular application. Spring selection should be considered alongside the motor, gear ratio, piston, spring guide, compression system, battery, wiring, and other internal components.

Adjust the Completed Build

Changing the spring may alter the muzzle velocity or energy of a compatible AEG. The actual result must always be measured with a chronograph after installation.

Complete an Internal Rebuild

A replacement spring may be installed during a broader gearbox rebuild involving the piston, gears, cylinder assembly, spring guide, bushings, bearings, motor, or electrical components.

AEG Compatibility

Maddog AEG Upgrade Springs are intended for use with many conventional electric airsoft gun gearboxes. The included Maddog guide card describes them as compatible with most standard AEGs; however, fitment is not universal.

Common platform types that frequently use standard AEG-style gearbox springs include:

• M4 and M16 style AEG rifles
• AK style AEG rifles
• MP5 style AEG platforms
• G36 style AEG platforms
• AUG style AEG rifles
• Other compatible electric airsoft guns using conventional gearbox springs

Compatibility must be confirmed before installation. Gearbox construction, spring dimensions, spring guides, quick-change systems, proprietary parts, and internal tolerances vary by manufacturer and model.

Compare the replacement spring with the original component and confirm that the spring is appropriate for your specific AEG.

These springs are not represented as compatible with every electric airsoft gun. They are not intended for gas blowback rifles, airsoft pistols, non-AEG spring rifles, or proprietary systems unless fitment has been independently confirmed.

Spring Rating Does Not Guarantee FPS

Ratings such as M100, M120, M140, and M150 identify general spring-strength categories. They should not be treated as exact muzzle-velocity specifications.

Final chronograph results may be affected by:

• Cylinder type and cylinder volume
• Piston-head and cylinder-head air seal
• Nozzle length and nozzle seal
• Hop-up chamber and bucking condition
• Inner-barrel length and internal diameter
• Spring precompression or spacers
• Gearbox construction and alignment
• Component wear
• BB weight
• Chronograph settings and testing conditions

Two different AEGs using the same spring rating may produce different results. Always measure the completed build rather than relying on the spring number or printed guide alone.

Any values shown on an included spring guide card should be treated as approximate reference information only. Variations may occur.

Stronger Springs Increase Gearbox Load

A stronger spring generally requires additional force to compress. This can increase the workload placed on the gearbox drivetrain, motor, battery, wiring, and other internal components.

Before installing a higher-rated spring, inspect and evaluate:

• Gearbox shell
• Piston body and piston rack
• Sector, spur, and bevel gears
• Spring guide
• Bushings or bearings
• Motor condition and torque capability
• Battery output and connector condition
• Wiring, trigger contacts, or MOSFET
• Gear shimming
• Motor height
• Angle of engagement
• Compression components and air seal

Higher-rated springs may require upgraded or reinforced supporting components. The exact requirements depend on the individual AEG and complete gearbox configuration.

Do not select a spring solely because it has the highest available rating. A balanced and properly assembled gearbox is more important than spring strength alone.

Installation & Safety Information

Opening an AEG gearbox may expose internal parts under substantial spring tension. Improper disassembly, installation, or reassembly can damage the airsoft gun, release components unexpectedly, cause injury, or affect the manufacturer's warranty.

• Remove the magazine and confirm the airsoft gun is unloaded
• Clear the hop-up chamber
• Disconnect and remove the battery
• Wear suitable eye protection
• Follow the manufacturer's disassembly instructions
• Maintain control of the spring and spring guide
• Release stored spring tension carefully
• Inspect the gearbox and internal components before reassembly
• Confirm the spring is seated correctly
• Do not force an incompatible spring into the gearbox
• Test operation carefully after reassembly
• Chronograph the completed AEG before gameplay

Professional installation is recommended unless you are experienced with AEG gearbox disassembly, spring tension, shimming, motor adjustment, drivetrain inspection, and safe reassembly.

Chronograph Testing Is Required

Chronograph the airsoft gun after replacing the spring or changing any major gearbox or compression component.

Test the finished AEG using the BB weight and measurement procedure required by the field where it will be used. Confirm compliance with all applicable:

• Muzzle-velocity limits
• Energy limits
• Weapon-class restrictions
• Minimum engagement distances
• Chronograph procedures
• Local field rules

If the completed AEG exceeds an applicable limit, stop using it until an appropriate spring or gearbox configuration has been installed and verified.

What's Included?

• One Maddog progressive AEG upgrade spring in the selected rating
• One Maddog upgrade spring guide card

Packaging Notice: Packaging style, guide-card design, labels, spring color, surface finish, and product presentation may vary between production runs. The spring rating selected through the product options determines the item ordered.

Specifications

• Brand: Maddog
• Product Type: Airsoft AEG replacement and upgrade spring
• Spring Design: Progressive, non-linear variable-pitch coil design
• Available Ratings: Select from currently available product options
• Intended Platform: Compatible Airsoft Electric Guns
• Primary Applications: Maintenance, repair, replacement, and custom gearbox tuning
• Installation Difficulty: Intermediate to advanced
• Professional Installation Recommended: Yes
• Chronograph Required After Installation: Yes
• Package Quantity: One spring

Maddog Pro Tip

Build for balance—not just spring strength. Match the spring to the gearbox shell, motor, gears, piston, spring guide, compression system, battery, intended use, and local field requirements.

The strongest available spring is not automatically the best choice. A properly matched and carefully assembled AEG setup is generally preferable to increasing spring resistance without evaluating the rest of the system.

Bottom Line: Maddog Progressive AEG Upgrade Springs provide multiple strength options for repairing, maintaining, or tuning compatible electric airsoft gearboxes. The non-linear variable-pitch construction is easy to identify by its changing coil spacing, while actual performance depends on the complete build.

Choose the right rating. Verify the fit. Chronograph the build. GAME ON!