So, you got your first AEG, you’ve skirmished with it a few times, and figured out you like the hobby enough to invest some time and effort into upgrading it. Well here are some things for you to consider. First off, we’ll assume you have a decent mid-level or high end AEG, with a minimum of having a metal or polymer body and a metal gearbox. If you have ANY of those plastic Wal-Mart / Dick’s Sporting Goods Softair type guns, STOP reading here, your very first upgrade should be a new AEG. For the sake of this topic, I’ll accept that even JG, DBoys, and CYMA AEGs can be upgraded to a certain limited extent.
I’ll leave it to you to decide when you want to upgrade, my personal belief is that if it isn’t broken don’t try to fix it. Other than cleaning up and reshimming, which I consider maintenance and not an upgrade, I’ll use a stock AEG as is until something breaks or wears out. After all, you paid good money for it, might as well get your moneys worth out of the parts.
A quick note on tech’ing, every good Airsoft player should consider learning enough about your AEG to be able to do rudimentary maintenance on it, such as cleaning the inner barrel, replacing a fuse, and adjusting the motor height. Having a working knowledge about what’s inside a gearbox and how all the parts interact with each other, not only helps you trouble shoot any problems, it also helps you pick out the right parts and understand what your favorite Tech is trying to explain to you.
So, this guide will hopefully help you make informed decisions on what to upgrade and what to look for when picking out your parts. I’ll break it down into two categories, Compression and Drive-train.
Compression upgrades are usually the easier and cheaper upgrades, giving a noticeable improvement right off the bat. These upgrades work with your existing drive-train and do not increase the stress on any other parts. They can be done individually or as a group without fear of breaking stock parts. The objective here is to minimize air loss and send it down the barrel. A simple compression test done while the gear box is disassembled, by placing your finger over the air nozzle while quickly plunging the piston in the cylinder, will show how good your set up is.
First and foremost, the easiest upgrade is to replace your hop-up bucking and inner barrel, this is especially true on low-end budget guns from China. A quality tight bore inner barrel, 6.04mm to 6.01mm, and a good bucking can make better use of the compressed air provide, put a better backspin on the BB and improve the air seal around the air nozzle, thus improving range and accuracy and usually adds about 20 – 30 FPS. Barrels are available in Brass, Stainless Steel, and Aluminum, and at a wide range of prices accordingly. I find Brass is a good compromise of cost and strength, though I prefer Madbulls 6.03mm Ver 2 Black Python hard anodized aluminum barrels. You have to be a little more careful working with them, but they are lighter and cheaper than Brass and Stainless Steel. A couple of things to bear in mind, always use quality BBs in tight bore barrels and clean it on a regular basis. The tighter the barrel, the more susceptible it is to jamming due to dirt or deformed BBs. Check the specs on your AEG, if you have a high-end AEG, chances are you already have a tight bore installed. I have seen several individual upgrade a KWA’s 6.04mm barrel with a Systema 6.03mm barrel, and then complain that there wasn’t any improvement. Yes, it is hard to tell just how much 1/10th of a millimeter is doing. However, most budget AEGs come with a 6.10mm to a 6.08mm inner barrel, and for a reason too as most beginners haven’t learn the value of a clean barrel or a quality BB yet. 6.08mm is a lot more forgiving than 6.01mm. For them, a tight bore barrel will make a difference.
Your bucking is one of the most abused parts in your gun and usually the first item to wear out. Made out of a balance of rubber and silicone, they make contact with the BB and produce the back-spin that generates the lift that keeps your BB in the air longer. Buckings should be matched to the FPS of the AEG; the higher the FPS, the less contact or grip the bucking needs to produce the back-spin. The more rubber in the bucking, the more grip it gets. Additionally, different brand inner barrels have slightly different outer dimension, so a bucking need to fit snugly over it to ensure a good air seal. Finally, the face of the bucking should mate up flush with the tip of your air nozzle, also to ensure a good air seal. There are so many options out there, that you just need to try and experiment to find the best one for your set up, but now you know what to look for. I will recommend Guarder’s 50% Clear (<400 FPS) and 70% Black (>400FPS) Hop-up Buckings as a good starting point. If you pass this selection, you can add the vast array of hop-up nubs to the equation; personally I stick with the little black tube.
Your Hop-up Housing shouldn’t need upgrading unless it breaks; there are a few good ones out there for most common AEGs like M4 / M16s, AKs, MP5s and G3s. Things to look for are a smooth feed tube and a solid adjuster that doesn’t creep with use. Speaking of M4 / M16s, there are two types for them depending on how they open up; One-Piece Hop-Ups for M4 / M16s that slide apart and Two-Piece Hop-ups for those that pivot around the front body pin to open.
Next in the compression chain is the Air Nozzle, these are pretty straight forward and easy to understand. They are what completes the seal between the gear box and the barrel, and loads the BB into the hop-up unit. Main thing to look for here is how well they seal around the cylinder head. Available in both metal and plastic, good ones will have an ‘O’ inside them to improve the seal. Air Nozzles are AEG specific, and again there are two types for M4/M16s as mentioned above.
The Piston Head, Cylinder Head and Cylinder are the work horse of the compression chain. The Piston Head, mounted on the end of the piston, is a valve of sorts. It opens when being retracted and slams shut when the piston moves forward. This is done by a loose fitting ‘O’ Ring that moves back and forth to seal against the cylinder wall and the rear half of the piston. The ‘O’ Ring is another high-wear item like the bucking, that is an easy upgrade even to the stock piston head, however, if properly lubed it should last quite a while. Use the compression test to determine the best ‘O’ ring through trial and error. Then test again without your finger over the air nozzle, the piston should slide back and forth with very little resistance. Piston Heads themselves come in two flavors; Ported (or Vented) and Unported, and Ball Bearing or not. Ported Heads can draw air from behind the piston where as Unported pulls all its air from down the barrel (and hopefully your BB has left the barrel before this happens) The advantage of one over the other depends on what kind of set up you are building, the Ported is good for high RPM as it allow a greater air flow as it moves back and forth, and is a good general purpose one as well. The Unported is good for higher FPS, as it seals up quicker and thus can move more air down the barrel. They do however; need a cylinder that is matched to the inner barrel length to prevent the dreaded ‘Suck Back’ if the BB hasn’t left the barrel yet. Ball Bearing refers to the rear of the piston, where your Main Spring presses up against the inside of your piston. The ball bearings allow the spring to twist easier as it compresses, which reduces friction and increases speed. When used along with a Ball Bearing Spring Guide, it can also precompess your spring up to half an inch. You also have your choice of metal or polymer; metal is stronger (FPS), but polymer is lighter (RPM). If you choice metal, make sure it or the cylinder head has some kind of padding on it. Metal-on-Metal impacts transfers all that stress into the front of the gear box leading to premature failure. There are also “Silent” piston heads that feature a rubber bumper or head to absorb the impact noise against the cylinder head.
Cylinder Heads are pretty straight forward as well. They are gear box specific. Available in metal and plastic, the metal ones are usually better. The plastic ones tend to be multi part affairs that trap a metal pipe in between them and I have seen quite a few of them fall apart over time. The best feature to look for is the double ‘O’ ring that seals it against the inside of the cylinder. With two ‘O’ rings you have less chance of a leak and it stabilizes it within the cylinder.
Cylinders are matched to your barrel length and are categorized by the location of the vent hole. Type ‘0’ has no vent and is good for up to a 590mm barrel, while Type ‘4’ has its vent almost in the middle and is used for extremely short barrel as found in the MP5K. Unless you are installing a longer barrel or you accidentally stepped on it while disassembling it, your stock cylinder should be up to the task.
A word on Bore-up Sets, a bore-up set is an advanced option available for longer barrels and high speed set-up. They have a slightly larger interior volume in the cylinder and a slightly larger opening in the cylinder head and air nozzle. As well as a larger piston head to match the cylinder. If you are installing a 650mm barrel in a DMR type M16, then a Bore-up Set with a Type ‘0’ cylinder would be an excellent choice. On high speed set-ups, ported bore-up cylinders can produce the same volume of air with less rearward movement, meaning a short stroked piston (more on that in the next article) can move the same amount of air as a regular piston in a normal cylinder.
One final note on the Compression Chain, your stock components will perform a whole lot better if you take them out; clean them of all the cheap factory grease, and relube them with a quality silicone base Airsoft lube. You might just find out you don’t even need to upgrade.