Airsoft Gun Upgrades Guide

Airsoft Gun Modding and Upgrade Guide

After skirmishing with your cool AEG a couple of times, you'll get so hooked that you may want to invest some time and effort into leveling it up. Here are a few crucial tips that you should consider to get the most out of your AEG upgrade for a durable and flawless performance. Assuming you either have a mid-level or high-end AEG such as the Lancer Tactical LT-19, upgrades can be done both internally and externally. In case what you use is a plastic Dick's Sporting Goods or Walmart Softair type you should invest your money into a quality weapon rather than upgrades. You should first start by upgrading to a brand-new gun such as the Lancer Tactical M4 Generation 2 before you continue reading this piece. Even so, I have to admit that even the CYMA, DBoys, and JG rifles can only be upgraded up to a certain degree; for instance, you can't just throw in 150% spring to your M16 Airsoft and suddenly turn it into a sniper level 450 FPS BB monster spitter.

How to Upgrade Your Airsoft Gun, Airsoft Gun
Figure 1: Airsoft Gun Assembly Source: Gohnarch at the German language WikipediaAirsoftgun EinzelteileCC BY-SA 3.0

Why You Should Upgrade Your Airsoft Gun.

Generally, most guys believe that upgrading airsoft guns isn't really necessary, especially if you carry out proper cleaning maintenance procedures as we previously discussed in several posts here. After all, since you paid handsomely for your gun, you should do your best to get your money's worth from the use of your piece. True enough, ‘if it ain't broke, don't fix it'.

Why You Should Upgrade Your Airsoft Gun
Figure 2: Jing Jong M4 Airsoft Gun Source: Jing Gong (JG) M4 or M4A1 airsoft gunCC BY-SA 3.0

However, real Airsoft enthusiasts prefer pushing their guns further for a more exciting performance. If you are that type of person, here are a couple of tangible reasons why upgrading your Airsoft gun is a good idea and how to actually do it. Shop hundreds of different upgrade parts in our online store once you've read this!

1. Durability

During the first maintenance session of your Airsoft gun, you should automatically start considering your gun upgrades because you'll be able to figure out the parts that wear out faster or those that need replacement. So, the most basic forms of upgrades for your gun may include movable part replacements such as a metal spring guide and metal bushings. However, since lots of modern Airsoft guns come with these parts pre-installed, ensure that you check the rifle's gearbox first before you start ordering any upgrade parts.

The most popular parts for durability upgrades include:

  • the suitable version and size of spring guide,
  • the suitable size of metal bushings
  • full steel tooth piston

2. Performance Upgrades For a Final Velocity of up to 350 FPS

When upgrading your Airsoft gun for better performance, you should start with the internal barrel and the hop up unit, and then move to the gear ratios.

Moreover, if you switch to a battery with a capacity of 9.6V or higher, you will easily boost the rate of fire. However you should only use a higher battery capacity after installing aftermarket gears. Otherwise, you risk premature failure of the stock gear.

The most popular parts for significant velocity upgrades include:

  • 6.03MM tightbore barrel
  • M100 spring
  • 9.6V NiMh battery
  • High speed gearset
  • Metal spring guide
  • Metal bushings
  • Hop up bucking and nub
  • Metallic or reinforced tooth piston

3. Higher Velocity Upgrades For a Final Velocity of over 350 FPS

You have to carefully consider each of the upgrade parts for perfect compatibility if you are to achieve over 400 FPS. Unfortunately, even after you assemble a perfect combination of the piston, spring, high torque gears and the motor, premature wear may still be a factor at the end of the day.

For a Final Velocity of over 350 FPS, some of the most popular Airsoft upgrades include:

  • 9.6V NiMH batteries
  • M110 or higher spring
  • High torque motor
  • High torque gears

Note: Above anything else, you should begin by addressing the power needs of your upgraded weapon. That's because high speed and high velocity Airsoft are colossal power hogs. For example, the majority of the 8.4V NiMh Airsoft batteries are only capable of cycling your Airsoft gun on full automatic mode in sporadic bursts of fire for just a few minutes before requiring a recharge! And even worse, if you constantly use your gun this way, it will lead to premature wear on your motor.

Higher Velocity UpgradesFor a Final Velocity of over 350 FPS
Figure 3: 9.6V Airsoft Battery Pack Source: BrokenSphereTenergy 9.6V 1400 mAh battery packCC BY-SA 3.0

How to Upgrade Your Airsoft Gun

Now that you already have an idea of the advantages of upgrading your Airsoft gun as well as a quick overview of how it's done, it's time to dive into the details of how you should actually do it. To make things easier and more digestible for you, we'll cover the upgrading mechanics by breaking them into two main classes;

  • the Compression System
  • the Drive Train

A. The Compression System

Generally, compression system upgrades tend to be simpler and less expensive and the best thing about them is that you'll notice a substantial improvement right away. They work harmoniously with your current drive train and other parts of your Airsoft Gun will not experience any kind of unnecessary stresses. You can either carry out single or grouped compression upgrades without worrying about breaking any of the stock parts.

The main aim of these types of upgrades is minimize the loss of air and direct it down the barrel of your airsoft gun.

Note: You can easily carry out a simple compression test when the gear box is dismantled. Just plunge the piston quickly in the cylinder why putting your finger over the air nozzle. This is a straightforward indicator of the status of your setup.

Barrel Upgrades

The simplest way of giving your Airsoft a quick upgrade is by replacing the hop up bucking plus the inner barrel particularly if you have China made low-budget guns. In most cases, Airsoft guns come with a 6.10mm barrel fitted by the manufacturer. For a simultaneous boost of velocity and accuracy, simply add a 6.03mm tight bore barrel then properly fit a hop up nub and a bucking set. Any high quality tight bore inner barrel of between 6.03 and 6.01mm and a suitable bucking will lead to better use of the compressed air of your gun. In addition, this will bring an improved backspin on your gun's BB's and augment the air seal that's around the air nozzle of your gun. As a result, the accuracy and range of your gun will significantly improve and you'll get an extra 20 to 30 FPS.

The Compression System
Figure 4: Field Stripped Airsoft Assembly Showing 1 - Barrel, 2-Slide, 3- Receiver, 4- Recoil spring. Source: Wikipedia Creative Commons

Barrels are usually available in lots of different materials and compositions such as Aluminum, Stainless Steel, and Brass, with prices varying from one type to another. Among all these, brass is a great choice that balances both quality and cost. However, for the best performance on a budget, the 6.03 Madbulls Version 2 Black Python barrel which is made from hard anodized aluminum is an excellent choice. You just have to be extra keen when using them particularly since they are way lighter than Stainless Steel and Brass. Some of the things that you have to keep in mind include:

  • You should start using high quality precision type BBs exclusively once you install a tight bore barrel.
  • To prevent any excessive jamming of your upgraded kit, ensure that you properly clean your barrel right after every use. That's because the tighter your barrel is, the more susceptible it becomes to jamming as a result of dirt from deformed BBs.
High Precision BBs
Figure 5: High Precision BBs Source: SorrunoAirsoft pellets 0.20gCC BY-SA 4.0

*Before considering any kind of upgrades, make sure that you counter-check your AEG's specs. If you already have a high-end piece, there's a good chance that it already has a tight bore installed by the manufacturer. An upgrade from a manufacturer's 6.04mm tight bore to a new 6.03mm barrel will hardly make any tangible improvement! On the other hand, regular budget AEGs will come with an inner barrel of anywhere between 6.10mm and 6.08mm.

Hop Up Bucking & Nub Upgrades

The bucking of your AEG is one of the fastest parts to wear out probably because it's also among the most abused parts. It is usually made of a combination of silicon and rubber and it's the part that comes into contact with the BBs and produces a back-spin that creates the lift which keeps the BBs in the air for a little longer. Therefore, you must match the buckings with your AEG's FPS. In essence, the higher the FPS you are looking to achieve, the less grip or contact the bucking will require to create the backspin and the more rubber your bucking has, the more contact it will have. Lastly, the bucking's face should flush with the air nozzle's tip to guarantee a good air seal. There are a vast range of options out there but then a good starting point for less than 400 FPS is Guarder's 50% Clear while for anything above 400 FPS, 70% Hop Up Buckings are great choices.

Hop Up mechanism gif animation
Figure 6: Hop Up mechanism gif animation Source: BeadleBHop-up animationCC BY-SA 3.0

When it comes to the housing of the Hop Up, no upgrades are needed unless there's a breakage. Many great options are available out there depending on your AEG. In case you are looking to replace yours, go for something with a smooth feed tube plus a solid adjuster that does not creep with continuous use.

The Air Nozzle

This is the part that completes the seal that comes between the barrel and the gear box and loads your BBs into the Hop-Up unit. For the best fit, look for air nozzles that have an "O" in their interior parts because these improve the seal. Make sure you find a suitable one for your specific AEG.

Piston and Cylinder Assembly

Depending on the kind of setup that you are looking to achieve, there are two types of piston heads; i.e. Vented/Ported and Unvented/Unported. Ported piston heads draw air from the posterior side of the piston while the unvented types pull air from the lower end of the barrel (the BB should have left the barrel before this takes place). Generally, the Ported piston heads are better for high RPM since they provide an allowance for richer flow of air in the course of the back and forth movement. This type is actually much better for general purpose AEGs such as the Lancer Tactical LT-02D M4 CQB. If what you want to achieve is a higher FPS, then you're better off with the unvented piston head type since the sealing up process is much quicker and therefore, more air can be moved down the barrel. To prevent any kind of suck-back in case the BB hasn't already left the barrel, ensure that that the cylinder is matched to the inner length of your barrel.

For cylinder heads, they are usually available in two types based on their material; i.e. metal and plastic. In most cases, metal cylinder heads are better especially since their plastic counterparts have multi-part fittings that end up trapping a metal pipe in their midst and as a result they are more susceptible to failure. When you are looking to replace your cylinder head, look for one with double O-rings that provide better stabilization within the cylinder and do a better job of preventing leaks.

Cylinders on the other hand are classified with respect to the length of your barrel and the position of the vent hole. There is the Type ‘4' cylinder which has a vent nearly at the middle and it's best for barrels that are quite short, for instance in the MP5K. For longer barrels on the other hand, the Type ‘0' is better and it doesn't have a hole. The Type ‘0' cylinder is good for barrels of up to 590mm. In case you are looking for something more advanced here; for instance installing a 650mm barrel then you can throw in a bore-up set which is excellent for a high speed setup with much longer barrels. That's because bore-up sets have a slightly bigger internal cylinder volume and the opening in the air nozzle and cylinder head is slightly bigger as well.

B. The Drive Train

Compared to the compression system, the drive train upgrades are a little more complicated. In this particular section, you should brace yourself for a hefty influx of technical whys and wherefores because you'll often have to upgrade a single item and reinforce others as well. Here, we'll break down the drive train upgrades into two main categories; Mechanical and Electrical upgrades. However, since we already comprehensively covered electrical wiring repairs and upgrades such as MOSFETs, connectors and the trigger switch on a previous post we're going to focus on mechanical upgrades of your Airsoft.

I'll try to keep it as simple and as precise as I possibly can.

Mechanical Upgrades

When you are going ahead with a drive train upgrade, there are four main classes of upgrades that you're looking to achieve. They are:

  • High Speed (CQB)
  • High Power (Woodland)
  • High FPS/RPM
  • A medium ground between a decent RPM combined with an adequate FPS

So, as you plan your upgrade, think about what you are looking to achieve, carefully consider your budget. High FPS/RPM upgrades will cost you a pretty penny so you have to be ready to dig deep into your pockets.

The Main Springs

Obviously, the main spring is the first thing that most of us Airsoft fans upgrade when we are looking to boost FPS. That's because it's the driving force of everything else that you'll find in your gearbox. When you switch to a stiffer spring, you'll also have to replace any plastic bushings with ones made of metal since a stiffer spring will exert more pressure.

Any spring upgrade of between M110 and M130 will mean replacing the casted pot-metal gears and reinforcing the piston heads as well. Furthermore, if you don't throw in a stronger motor and battery to your setup there may be no adequate power to give the new spring a full compression and thus it may result in gearbox lock-up. Any spring above that means that you will have to construct another gearbox from the ground up. If you don't do that, don't expect your setup to last for long as it will eventually succumb to the spring pressure.

On the same note, replace any plastic spring guide (plastic tends to shatter and the shrapnel may lead to much worse damage within the gearbox) that you may find in your gearbox with a metal one and go for a ball bearing version if you can so that you can allow the spring flex smoother by minimizing the stress.

The Pistons

There are a vast range of pistons available depending on what you are trying to achieve for your airsoft. They include:

  • Half-tooth pistons: it only has a portion of the teeth molded and increases the torque for higher gear ratio to for better compression of the main spring. Best suited for high FPS setups with high torque up gears.
  • Full-tooth Pistons: suitable for higher speed and general purpose Airsoft use
  • Short stroke pistons: have a few teeth taken out to reduce the distance that the piston retracts and the magnitude of compression that is imparted on the spring.

The body and the teeth of the pistons can come crafted in a range of material such as synthetic or nylon which are lighter for higher RPM while those made of aluminum alloys are better for higher torque and FPS. Since the piston is perhaps the hardest working item in your AEG, you better not go cheap while going for an upgrade!


Another great way of boosting the performance of your Airsoft gun is through installation of high speed gears. In essence, high speed gears come with a lower tooth ratio and thus, they upgrade your Airsoft gun's ROF (rate of fire). Stock guns usually have a firing rate of about 12 BB's per second or rather 720 BB's per second. Once you install high speed gears your ROF will get to more than 20 BB's per second and you won't even have to make any adjustments to the motor as long as you keep the FPS at a maximum of 350. For a higher FPS, then you'll have to do something extra with the motor and battery pack.

Figure 7: Airsoft Gearbox Cross-section View Source: Skiler-2Gearbox de una aegCC BY-SA 3.0

In case you encounter feeding problems, you can improve the feeding reliability with a Sector Gear Delay Clip. It basically slips over the tappet plate on the sector gear's post to increase the amount of time in which the tappet plate stays in position to allow the BB to raise up to the hop up unit.

If you are more about power and torque, you can go for gears with higher torque ratios and super torque ratios. For general purpose AEG use, you should go for gears with Standard Ratios.

As a rule of thumb, make sure that you get the piston and the gear from the same manufacturer so that you can guarantee that they are of the same pitch for optimal meshing. And by the way, this will also significantly reduce the intensity of noise produced.

Bushings & Ball Bearings

Since this is a pretty obvious topic, I'll just brush through the most important parts. First of all, you should know that bushings are most suitable for general purpose applications since the rate of motion is lower. Whenever you replace a bushing, ensure that it snugly sits in the hole as any slack will result in premature failure since it will move around much more and wear out faster. Mind you, this may mean that you'll require a whole new gearbox!

For high speed applications of your AEG, ball bearings perform best but they are a little more complex compared to regular bushings. Their performance is exemplary for M100 and M110 springs and can reliably support up to M130 springs. To prevent premature failure especially when you use a heavy spring ensure that you choose a ball bearing setup whose balls are visibly larger than the bushing of the ball bearing itself.

Motors and Batteries

Just like the gears, motors also come in High-Speed, Standard and High Torque capacities. Since you buy a complete assembly of these, there's really nothing to talk about but you should just know that the harder the motor works, the higher the battery capacity it will need. A word of advice is that if a motor works too hard, it may heat up excessively and will eventually weaken the synthetic magnet's magnetic charge and the lacquer insulation may be burnt off the armature's wire windings. This drastically reduces the effectiveness of the motor and may even lead to permanent damage. In case you notice the motor heating up excessively either increase the gear torque or reduce the spring.

For proper installation of a large sized battery, you will need a larger gun stock or find a way of securely mounting the battery to your gun. Most of the Airsoft gun designs are not made with an accommodation to fit extra-large batteries. Therefore, you will have to use a battery bag that is externally mounted such as a replica laser battery box or swap the stock on one of the holding stocks of the CQb battery. Thankfully, the more recent LIPO style Airsoft batteries come packed with more power for a smaller size and they perform quite well for Airsoft guns that have been properly upgraded.

Well, that's it for Airsoft gun upgrades today. With what we've covered so far you can be assured of carrying out more functional, durable and efficient upgrades even if you are just a beginner!