Your Complete Buying Guide to Choosing the Right Airsoft Gun Spring

Whether you're chasing a specific FPS target for your local site's limits or breathing new life into a tired AEG, swapping out your airsoft gun spring is one of the simplest and most cost-effective upgrades you can make. In this guide, we'll walk you through the different spring types, how ratings work, and how to pick the perfect spring for your setup — so you can buy with confidence and get back on the field faster.

Why Buy Your Airsoft Rifle Spring From Us?

We stock a huge range of springs from trusted brands like ASG Ultimate, Nuprol, Lonex, Specna Arms, and Classic Army — over 10,000 airsoft products across the store, in fact. Every order benefits from our price match guarantee, so you'll never overpay. We also offer free UK shipping on orders over £75 and fast dispatch on in-stock items, meaning your upgrade arrives quickly. And if you're unsure which spring suits your gun, our expert customer support team is always happy to help you find the right fit.

Understanding Airsoft Spring Ratings

Airsoft springs are labelled with an "M" rating — M90, M100, M110, M120, and so on. This number loosely corresponds to the metres-per-second (m/s) velocity the spring should produce in a standard AEG gearbox under ideal conditions. In practice, your actual FPS will vary depending on barrel length, air seal, hop-up unit, and BB weight, but the M-rating gives you a reliable baseline for comparison.

Low-Rate Springs (M90–M100)

These are ideal for CQB sites with strict FPS limits (typically around 350 FPS on 0.20g BBs). An M90 spring like the Classic Army SP90 or ASG M90 SSG24 spring keeps your gun comfortably within close-quarters limits and also reduces stress on your gearbox internals, extending the life of your piston and gears.

Mid-Rate Springs (M105–M120)

The sweet spot for most outdoor AEG players. Springs such as the ASG M105 Ultimate or Hwasan SP120 will typically put you in the 350–400 FPS range, which suits the majority of UK woodland and milsim sites. If you're running a standard V2 or V3 gearbox, this is where most players end up.

High-Rate Springs (M130–M190)

Designed primarily for airsoft sniper rifles and DMRs, these heavy springs push FPS well above 400. The ASG M150 and M190 SSG24/MOD24 sniper springs are popular choices for bolt-action platforms that allow higher energy. Be mindful that running a spring this stiff in an AEG usually requires reinforced internals — a stronger piston, a metal-toothed rack, and a quality spring guide with a bearing.

Types of Airsoft Springs and What They Fit

AEG Springs

The most common type. These sit inside your gearbox (V2, V3, V6/V7, etc.) and are compressed by the motor-driven piston assembly. Products like the Nuprol M100 Spring and the Battleaxe M100 AEG airsoft rifle spring are straightforward drop-in upgrades for most electric rifles.

Sniper Rifle Springs

Bolt-action platforms such as the ASG SSG24/MOD24 and Ares Amoeba Striker use platform-specific springs. The Ares AS-SP550 Striker spring, for example, is designed exclusively for the Striker chassis, while ASG's SSG24 springs come in M90, M150, M170, and M190 variants to let you fine-tune your sniper's output precisely.

PTW/CTW Springs

Professional Training Weapon systems use a narrower-diameter spring. Nuprol's M90 and M110 PTW/CTW/Katana springs and the WE Tech Katana M100 cater to these specialist platforms, so make sure you're buying the correct type for your gun.

Spring Guides and Accessories

Don't overlook the spring guide — it keeps your spring centred and reduces wobble, improving shot-to-shot consistency. We carry guides from ASG Ultimate (V2, V3, and V6/V7 gearboxes), Specna Arms Enter & Convert metal guides, and the ASG Scorpion EVO bearing spring guide. A bearing-end spring guide is a worthwhile addition because it lets the spring rotate freely during compression, reducing wear and delivering smoother cycling.

M90 Spring vs M100: Which Should You Choose?

This is one of the most common questions we see, so let's break down the M90 spring vs M100 debate. An M90 typically outputs around 300–330 FPS with 0.20g BBs, making it perfect for indoor CQB where site limits are tight. An M100 pushes that up to roughly 330–360 FPS, which works for most outdoor skirmish sites in the UK. If you predominantly play indoors, go M90. If you're mostly outdoors and want a little more range without straying into DMR territory, M100 is the better pick. Both place minimal stress on standard gearbox components, so reliability stays high either way.

Practical Buying Advice for Airsoft Springs

Check Your Site Limits First

Every UK airsoft site publishes FPS limits by weapon class (usually separated into assault rifles, DMRs, and bolt-action snipers). Always buy your spring with these limits in mind — going over means a failed chrono and sitting out the game.

Consider Your Gearbox Health

Jumping straight to an M150 in a stock AEG is asking for trouble. Stronger airsoft springs put more load on your piston, gears, and motor. If you're upgrading significantly, budget for reinforced internals or browse our full range of airsoft upgrade parts and accessories to ensure everything works together.

Match Spring to Platform

An AEG spring won't fit a PTW, and a Striker-specific spring won't work in a standard V2 gearbox. Always confirm compatibility before ordering. If in doubt, check the product listing or contact our support team.

Keep a Spare

Springs are consumables. Over thousands of shots, they lose tension and your FPS will gradually drop. Keeping a replacement airsoft gun spring in your kit bag means you're never caught out on game day.

Brand Spotlight: ASG Ultimate vs Nuprol vs Lonex

ASG Ultimate springs are made to mil-spec standards and colour-coded by rating — blue for M95, yellow for M105, orange for M125, red for M135 — making identification easy even mid-build. Nuprol offers excellent value with their piano wire AEG springs and PTW-specific options. Lonex springs, like the M130, are known for consistent output and durability. All three are solid choices; the "best" brand often comes down to which spring rating and platform compatibility you need. You can explore our full selection of airsoft rifles and sniper rifles to see which platforms pair well with these springs.

Frequently Asked Questions

What FPS will an M100 airsoft gun spring give me?

In a typical AEG with a good air seal, an M100 spring produces approximately 330–360 FPS with 0.20g BBs. Actual output varies with barrel length, cylinder volume, and hop-up setup, so always chrono your gun after fitting a new spring.

Can I fit an airsoft rifle spring myself?

Yes — spring swaps are one of the more accessible DIY upgrades. For most AEGs, you'll need to open the gearbox, which requires basic tools and patience. Bolt-action sniper rifles are even simpler, often requiring just the removal of a few pins or screws. If you're new to teching, check out guides on our blog or ask our team for pointers.

Do I need to change my spring guide when upgrading?

Not always, but it's strongly recommended — especially if you're moving to a significantly stiffer spring. A metal spring guide with a bearing end reduces friction and ensures the spring compresses evenly, which improves consistency and longevity.

How long does an airsoft spring last?

A quality spring will typically last tens of thousands of rounds before noticeably losing tension. Piano wire springs (like those from Nuprol) tend to hold their rating longer than standard tempered-steel springs. If you notice your FPS dropping by 15–20 FPS from its original reading, it's time for a replacement.

Are airsoft springs universal?

Not quite. Most standard AEG springs fit V2 and V3 gearboxes interchangeably, but PTW systems, certain proprietary platforms (like the Ares Striker), and some sniper rifles require model-specific springs. Always double-check compatibility with your gun before purchasing. Our spare parts category makes it easy to find exactly what fits your platform.