Buying Guide: AEG Springs - What spring for what FPS?

AEG Springs - What spring for what FPS?

Before we start, ask yourself the question: "What does my AEG lack?" If you cannot answer this, you probably do not need an upgrade just yet. Upgrading an Airsoft AEG can make all the difference, but it can also make no difference if the wrong upgrade is installed for the desired outcome. 

A spring upgrade will increase your AEG's range slightly but will increase the wear on the internal components and shorten the AEG's lifespan in most cases. If it is more range you are after, we suggest first upgrading your HOP-up rubber, bucking, and inner barrel, and if you don't get the result you want then consider a spring upgrade. 

When considering what you want performance-wise from your AEG it is also important to stay grounded in the real world, and not to expect too much. These platforms are hamstrung by legality and safety and are never going to shoot like an Air rifle or real firearm. For more information on what level of performance you should realistically expect from your AEG, check out our AEG Performance and Maintenance guide. That said, thanks to the HOP-up system and ever-improving internal components, Airsoft AEGs are capable of very impressive performance and will beat out any other "non-lethal" combat sports alternative with ease!

Upgrading an AEG spring is easier than ever thanks to the widespread adoption of quick change spring systems, but if your AEG does not have a quick change spring we advise that you have your spring upgrade carried out by an Airsoft Tech to avoid the absolute nightmare that an AEGs internals can rapidly become if you don't have a clue! You have been warned!

M85 - 85m/s - 280 FPS on 0.2g BBs

An M85 spring, also known as an SP85 provides 280 FPS on 0.2g BBs in an AEG with acceptable air seal. This spring is the type which is provided stock in Tokyo Marui AEGs, keeping them in line with Japanese power regulations. 

M90 - 90m/s - 295 FPS on 0.2g BBs

An M90 spring provides 295 FPS on 0.2g BBs, and is ideally suited to Airsoft AEG's intended for CQB, as the additional power is not necessary for CQB ranges. Using a lower strength spring will prolong the life of the AEG's internals and provide a greater rate of fire and improved trigger response. 

M95 - 95m/s - 310 FPS on 0.2g BBs

An M95 spring provides 310 FPS on 0.2g BBs, and is generally what you will find installed into most UK spec. AEGs out of the box. These springs are used as they provide a happy medium between all out power and rate of fire, whilst allowing you to use the AEG outdoors and in CQB. 

M100 - 100m/s - 328 FPS on 0.2g BBs

An M100 spring, also known as a 1 Joule spring, provides 328 FPS on a 0.2g BB, lying in line with both the upper limit for Airsoft under Japanese law and the advised limits for many UK Airsoft sites. Many UK sites now allow up to 350 FPS, but we generally advise that you leave a buffer zone of FPS so you never risk having your AEG removed from play. 

When coupled with other upgrade parts, such as tightbore inner barrels, an M100 spring should see an AEG shooting at near enough 350 FPS with an M100, as such we recommend this spring for 350 FPS field limits if you are likely to upgrade your inner barrel or you have already. 

M105 - 105m/s - 344 FPS on 0.2g BBs

The M105 spring should provide 344 FPS on a 0.2g BB, meaning this is the absolute strongest spring you will want to install into your AEG if you intend to skirmish it. With a tightbore inner barrel installed, this spring can often push the FPS of your AEG above 350, due to the improved air seal. At this point, the strength of the spring will start to noticeably affect your rate of fire and trigger response, and if you are considering upgrading to this level it may be worth considering a high torque motor to keep that snappy performance with the increase in velocity. 

M110 - 110m/s - 360 FPS on 0.2g BBs

With an M110 spring installed you should expect 360 FPS on 0.2g BBs in an AEG with good air seal. We do not advise installing this spring if you intend to skirmish, as the likelihood is you will not be allowed to take your AEG out if fully automatic is still functional. 370 FPS is the absolute upper limit of legal muzzle energy for a fully automatic Airsoft gun in the UK, and beyond this, it is legally considered a Section 5 Firearm. We're sure we don't need to explain to you why you should never install any of the following springs into a full-auto capable Airsoft AEG. 

This spring will probably cause your AEG to exceed your local site's limits for muzzle energy and is dangerously close to the UK legal limit for fully automatic Airsoft guns. Proceed with caution if you are installing this spring. 

M120 - 120m/s - 393 FPS on 0.2g BBs

An M120 spring should provide around 393 FPS with a 0.2g BB. This is the spring we advise for DMR setups which are limited to semi-automatic only. With this spring installed in your AEG you will likely need a high torque motor and other internal upgrades due to the heightened stress this spring will place upon your gearbox internals and shell. 

When carrying out the balancing act of tuning your AEG to reach the absolute pinnacle of power it is important not to forget "joule creep". This phenomenon happens when heavier BBs are used and can cause the AEG's muzzle energy to creep up more than expected. When DMRs are chrono'd most sites insist on chronoing with the BBs you are using and will be keeping an eye on you over the course of the skirmish. This is important for keeping other players safe, so please ensure you have done your sums before putting together a DMR build to avoid disappointment! 

M130 - 130m/s - 426 FPS on 0.2g BBs

An M130 spring provides around 426 FPS with a 0.2g BB. This spring is intended for semi-automatic DMR rifles only, and the internals of any such setup should be thoroughly upgraded before the spring is installed if they are to survive. It is important to note that when using a DMR you are likely to be using heavy BBs, as such, it is important that you chrono your AEG on the weight of BB you are using, and carry out any muzzle energy calculations with these BBs. The alternative is to be caught out by the "joule creep" phenomenon, and have your AEG turned away from the skirmish site. 

So, that's that! You should now have a basic understanding of the different AEG springs available, what we advise to use for certain roles on the battlefield, and what to consider when shopping for Airsoft gun upgrades. If you feel like you are now ready to take the plunge, you can find our Airsoft AEG spring collection here