Untitled Document

F.A.Q

How does an airsoft gun work?

Airsoft guns work using a very simple mechanical process that forces air out a 6.09 mm tube ( the inner barrel ). There are 3 types of airsoft guns, electric, spring, and gas. Each works different to force the air out the barrel. Even though they work differently they all have one thing in common, compressed air and without it you do not have an airsoft gun.

Here are some common Airsoft terms and their meanings that I will be using in my explanations of gun operation:

Hop-up- This is a rubber sleeve called a bucking that wraps around the back end of the inner barrel. A small rubber piece called a nub pushes against the bucking. This forces a small amount of the rubber to touch the BB as it flies out the barrel. This puts backspin on the BB and allows it to move further through the air. Basically the backward spinning motion of the BB picks itself up as it flies through the air. It counters the force of gravity that wants to pull it down. Hop-ups are different on each type of gun but the method is the same. Some hop-up are adjustable by a dial or small set screw and some are fixed. Higher end guns will have an adjustable hop-up. This allows you to use different weight BBs without compromising trajectory and distance due to a fixed hop-up. A heavier BB will drop faster and requires more hop ( or backspin ) to compensate for this.

Compression- This is how much air is sealed in the cylinder during the firing sequence. Most techs including myself will rate a guns compression in percentage. So say I have a gun that should be shooting harder and further than it is. I will test the cylinder and piston and determine the amount of compression I am getting out of the firing action. If I push the piston into the cylinder with my finger over the cylinder head and can not push it in I say that it’s 100% compression. If I can push it in slowly I might call it 60% compression depending on how easily I can push it in. Loss of compression is simply the escape of air with the cylinder head sealed. This can be due to a multitude of reasons and I will not get into that here. So if I have 60% compression I am losing 40% during the firing of the gun. You want the most compression you can get out of your cylinder and piston. True 100% compression is impossible to achieve. There are several points that you will lose compression as the air travels from the end of the cylinder head to the hop-up. You can however achieve 100% between the piston head and the cylinder head.

Slide- This is the upper part of an automatic pistol that slides back to cock the gun and chamber a round.

Real Steel- Real firearms that fire bullets rather than 6mm plastic BBs.

Green Gas- This is propane with silicone added to it. There is a misconception that it is special. It is not. I use Colman brand propane and add silicone oil to the valve before I attach my adapter, presto... Green Gas. Propane is a great deal cheaper and easier to get than green gas.

Mag ( Magazine )- This is the clip that holds the BB’s. This will also hold gas in gas airsoft guns.

Spring Airsoft gun:

Key components:
spring
spring lock
trigger
cylinder
piston
hop-up ( not on all models )
inner barrel

The spring airsoft guns works by manually pulling the spring back until it locks into the fire position. The trigger will release the spring lock and allow the spring to push the piston forward inside the cylinder. The piston has an o-ring or rubber collar on the end that seals the air inside the cylinder. This leaves the only place for the air to go is out the barrel. When the spring is set and the slide or bolt moves back into place it feeds a BB into the barrel just before the hop-up. When the air is forced out the barrel by the spring pushing the piston forward the air in the cylinder forces the BB to fly out the barrel. Then the spring has to be manually reset to the fire position.
There are several types of spring airsoft guns. Pistols (commonly referred to as “springers” ), shotguns, sniper rifles, assault riffles. Most of the spring airsoft guns are low end guns with the exception of some sniper rifles and shotguns.

Gas airsoft guns:

Key components:
chamber
mag
hop-up
hammer
slide ( on Gas Blowback guns GBB for short )

The gas airsoft gun is very different in comparison to the other 2 types. This type of airsoft gun does not use a spring to force air through a cylinder. It has a chamber of compressed gas (typically located in the magazine or clip). The most common gas airsoft gun is the pistol and that is the one we will be focusing on here. There are gas shotguns, sniper rifles, and automatic assault rifles but we will not get into those here as they are very much the same principal as the pistol with the exception of some shotguns. The gas pistol is the most common sidearm carried by serious players. There are two main types, the fixed slide and the gas blowback ( or GBB ). The difference between the two is the GBB has a moving slide and operates identical to its real steel counterpart and the fixed slide does not, the slide is fixed and does not move. I will use the GBB in my description. The gun works by inserting the magazine into the gun (after filling it with propane or green gas) and pulling back the slide. This does two things, locks the hammer back in the fire position and loads a BB into the barrel just before the hop-up. When you pull the trigger the hammer is released and it flies forward hitting the release valve on the mag. Gas shoots out the front part of the valve into a chamber where it is split to perform two actions. One is to force the slide backwards and reset the hammer then load another BB. Two is to force the loaded BB out the barrel. By the time the slide returns and loads another BB the loaded BB is gone. You are ready to fire again, just pull the trigger. On the fixed slide models the operation is the same minus the slide action. This gives you a little more air pressure dedicated to the firing of the BB. The hammer is reset as in the GBB model and all you need to do is pull the trigger to fire again. The fixed slide models will be more quiet than there GBB counterparts and can be silenced where as you can not really silence a GBB due to the slide action and release of gas there.

Automatic Electric Gun ( AEG ):

Key Components:
Battery
Hop-up
Inner Barrel
Mech Box
Motor
Mag

The AEG is the most common airsoft gun you will encounter at the field. This is the most intricate of the three types of airsoft guns and the most versatile as far as upgrading and custom set ups go.
These are full automatic guns and as long as you pull the trigger the gun will keep shooting BBs. I will break down each part of the AEG before I explain how it works.

Battery:
This is the power source for the AEG and comes in many types. There are 3 types of batteries available, Ni-Cad, NiMH, and the newest addition, Li-Poly.
Ni-Cad batteries were the first and are still used by some players. The thing to look out for with Ni-Cad batteries is the memory effect. You have to discharge the battery before you charge it. If you just top it off without discharging it the memory will set to only put a certain amount of amps into the battery. So if you charge a half charged 2000 mAh Ni-Cad without discharging the memory will set to only half charge the battery. You will only be able to charge it up to 1000 mAh.
The next battery is the NiMH (Nickel metal ) which is an all around great battery, and my personal choice. This battery does not have the memory effect of the Ni-Cads and you can top it off at the field with no worries of ruining you battery or having to wait for it to discharge. This is the most common battery used by players.
The third and newest choice is the Li-Poly. These are being used by some and there have been mixed responses. Some people love and swear by them and some want nothing to do with them. They hold a lot of power and runtime in a small light weight battery which is a definite plus. However there are some drawbacks. It is rather costly to start using Li-Poly as the chargers and the batteries are expensive. The next draw back is one I have looked into and have read warnings that they have a tendency to catch on fire. After researching this and speaking with several RC professionals this makes sense. Li-Poly batteries can have only so much constant current draw put on them. This depends on the battery. If the limit is passes for prolonged periods the battery will heat up to the point that it literally catches fire. AEGs put a heavy constant draw on batteries. This will happen if the battery gets shorted out also. If you are considering the Li-Poly battery do your research and get a battery that will handle the current draw of your gun. If you are new to airsoft or just do not know a lot about the guns I would stay away from these batteries, stick with NiMH.

Motor:
This is the driving force of the mech box. There are 3 main types, High Speed, Stock, and High torque. Most AEGs will run fine on a stock motor until you get up to a 120 and higher spring. I will go over springs in the mech box breakdown. High speed motors run best with a lower power spring. The motor has a small gear on the end which is called the pinion gear and is the starting point of the gear rotation inside the mech box.

Mech Box:
This is the heart of the AEG and where most upgrades are done. It in itself has to be broken down to fully understand how the gun works. I will start by listing each part of the mech box:

Shell
Bushings
Shims
Bevel Gear
Spur Gear
Sector Gear
Anti Reversal Latch
Spring
Spring Guide
Piston
Piston Head
Cylinder
Cylinder Head
Nozzle
Tappet Plate
Trigger Assembly
Selector plate

The shell is simply the housing for all the parts and it holds everything where it needs to be.

The bushings are what holds the gears in place and allows them to rotate. There are several kinds of bushings each with there own pros and cons. The first type is the plastic bushing. This bushing will typically make the mech box a little quieter but the wear out much faster than any of the other types. Second are bearing bushings. These also slightly make the box quieter and allow the gears to rotate with less friction. They last longer than plastic bushings but do wear out. The third type is the strongest and longest lasting. The solid metal bushing is designed to take whatever you can throw at it. They are not as quiet as the other two and add a little more friction to the rotation but they will last for years in a properly shimmed box.

Shims are small metal rings that come in different thicknesses. These are used to shim the gears to the ideal vertical placement in relation to each other. They also prevent the gears from moving vertically in the box. You want the gears to rotate without common in contact with the shell or each other while keeping the gears close so the teeth can mesh together with as much surface area as possible. If they do not mesh together enough the teeth will strip and if they are to close they will rub against each other and bind or create a great amount of friction. This will burn out your motor along with a multitude of other nasty problems. Shimming is one of the most important things as far as the mech box is goes and the reliability of the AEG.

The gears I will go over at one time as they make up one part of the box as a unit. The first gear after the pinion gear that is on the motor is the bevel gear. As the motor turns the pinion gear it in return rotates the bevel gear. The anti reversal latch engages the bevel gear and prevents is from rotating in the opposite direction. The bevel gear turns the spur gear that sits on the bottom of the box. The spur gear engages and turns the sector gear. The sector gear is the gear the pulls back the piston. It has two sets of teeth. One set runs all the way around the gear and meshes with the spur gear. The second set only runs part way around the gear and meshes with the teeth on the piston.

The piston is the part that the spring slides into and pushes the air out of the cylinder. It has a row of teeth on the bottom the mesh with the sector gear that pulls the piston back and then releases it. On the front of the piston is the piston head. This has an O-ring around the outside the presses on the wall of the cylinder. This is what creates your compression inside the cylinder. You want a good seal with as little friction as possible. Both the piston and piston head come in polycarbonite and aluminum versions. I would stay away from aluminum piston. If the teeth from the sector gear misalign and the piston binds up you will strip your gears. The polycarb pistons will break before the teeth on your gears strip. It is better the have to replace a $10.00 piston as opposed to a $60.00 set of gears and a $10.00 piston. I made this mistake and paid the price. There are a number of very strong polycarb pistons out there. As for the piston head either one will work fine but here are a few things to consider. The polycarb piston head will be more silent and will not put as much impact force on the weakest part of the shell, the end where the nozzle sticks out. The aluminum piston head is louder and puts undue stress on the end of the box which takes us back to the piston. The combination of an aluminum piston and piston head can blow off the end of the shell. Its just too much force slamming into the cylinder head. Finally there is the silent piston head. This is a polycarb piston head that has a rubber bubble on the end. This dampens the impact of the piston head against the cylinder head. Testing has shown however that the sound reduction in minimal and the set up needs to be right to really make it worthwhile. Most piston heads have small port holes in the end that allow air to push the O-ring out against the cylinder wall as the piston travels forward.

The cylinder is where the air is compressed and forced out through the cylinder head by the piston moving forward. Most pistons have a port on the side that allows air in when the piston is all the way back in the fire position. There is an after market cylinder called a zero cylinder that does not have the port hole. Its a solid cylinder and allows for more airspace to be compressed during the pistons movement forward. The cylinder head seals inside the far end of the cylinder and reduces the volume in the cylinder from about a 1 inch diameter down to 1/4 inch diameter. This increases the speed and force of the air as it leaves the cylinder. Again you have two choices on material, polycarbonate and aluminum. I prefer the aluminum just for durability but both types work fine up to a 120 spring. A 120 spring or higher I would recommend the aluminum type

The nozzle slides back and forward on the hollow tube that sticks out of the cylinder head. It directs the air into the hop-up and allows BBs to feed one at a time into their firing position. Most nozzles are polycarb but you can get metal ones also. I have both and each one works just as well as the other. The one thought I have about nozzle selection is that polycarb is a softer material than metal and could seal a little better in the hop-up, but this is just a thought.

The tappet plate locks onto the nozzle at its base and moves the nozzle back and forward as the sector gear turns. The sector gear has a small offset nub that pulls the tappet plate back on each rotation. A spring then pulls the tappet plate back to the forward position. As far as the brand of the tappet plate to get I would recommend an inexpensive one from Guarder or Systema. Its going to break, there is no getting around it. Don’t put a lot of money into replacing it thinking it will never break again, it will. On high rate of fire guns there can be a problem with BB feeding. The action of the nozzle is faster than the BB’s can feed into the hop-up resulting in random dry firing in full-auto. This can be resolved by adding a sector chip to the sector gear. This little piece of metal sets in between the gear shaft and the offset nub allowing the tappet plate remain back for a slit second longer. This gives the BB’s the time they need to feed into the hop-up.

The spring is the power house of the mech box and can change the whole dynamic of the AEG. Its largest influence is on the FPS (Feet Per Second ) of the gun. It also affects rate of fire, battery consumption, and longevity of the mech box and its components. This is the first thing most people upgrade in their guns and can be the most destructive on the mech box and its parts. Each company rates their springs differently and the most widely accepted scale is the Systema scale. This is the scale I will be using. Most AEGs come stock with a 90 or 100 spring. A 100 spring will generally give you around 320 FPS. A 110 spring will give you a range of 350 to 370 FPS and a 120 spring will put you right at 400 FPS in a stock gun with a 6.09 mm barrel. If you upgrade your spring, and at some point you will, you need to start upgrading the other parts of the box to reinforced ones. You will also want to get a reinforced shell if you do not already have one. I will go into more detail on FPS and springs later. For now I will just state that the spring is what pushes the piston forward in the cylinder and forces the air into the hop-up. The spring guide keeps the spring straight and prevents it from contorting under pressure. You can get spring guides that have a ball bearing at their base. This relieves stress on the spring and allows it to rotate as it is compressed.

Finally there is the trigger assembly and selector plate. The trigger assembly is simply a switch between the battery and the motor. When you pull the trigger it makes contact along the positive wiring and completes the circuit, thus turning the motor on. The selector plate positions components of the trigger assembly so cycle once for semi-auto or continuous current for full auto. The selector plate also engages a small plastic arm that blocks the trigger from being pulled which would be safe mode.

That makes up the standard mech box of most AEGs.

Hop-Up unit:
This is what gives your gun its range. Hop is simply back spin put on the BB so it will stay air born longer. The back spin counters the force of gravity and picks the BB up. You can see this by turning your hop-up all the way up and watch the BB when you shot, it should fly up into the air. This is obviously too much hop and you want to set the hop to allow the BB to glide out to its target. I set mine to have a slight rise at about 130 feet. This gives me a range of 200+ feet with a 390 fps gun. The unit is very simple and consists of the bucking, nub, and the unit itself. The bucking slides around the end of the inner barrel. The end of the barrel that has a notch cut into it is the top of the barrel. The barrel and bucking slide into the hop-up unit and lock into place. There is a dial or knob that will adjust an arm up and down inside the unit. This is where the nub goes. This is a small round piece of rubber. The arm pushes the nub against the bucking and forces it into the notch on the barrel. This allows the BB to come in contact with the bucking as it is fired and puts back spin on the BB. The dial will adjust the amount of bucking and pressure that the BB contacts and in turn puts more or less back spin on the BB.

Inner Barrel
This is the barrel the BB is fired out of and is separate from the outer barrel which is the one you see. This inner barrel slides into the outer barrel. Stock barrels are 6.09 mm inside diameter, a high end BB is around 5.96 mm. This is an ok barrel for engagements out to 75 feet. After that the grouping of the BBs is very large. If you want better accuracy and maintain the accuracy at further distances you will want to change this barrel out to what is called a “Tight Bore Barrel “. The tight bore barrels drop the inside diameter to 6.04, 6.03, and the most recent 6.01 mm. This will do two things for your gun, It will give the gun a small FPS increase and it will improve the accuracy of the BBs significantly as well as tighten the grouping. With a 6.03 mm you will be accurate out to 150+ feet. One warning about the tight bore barrel… only use high end BBs…. NOT the “big-box-store” kind. Poorly made BBs will jam in the barrel and you will destroy your mech box. You have been warned.

Magazine
Finally we have the mag. This is the clip that holds the BBs and feeds them into the gun. There are three main types for AEGs. You have the low and mid cap magazines, high cap magazines, and the largest of the three the electric box magazine. Most AEGs come with at least one high cap magazine. The low and mid cap magazines have a spring that snakes back and forth through the mag. It is loaded by pushing BBs into the port with a speed loader until the spring is fully compressed. These mags hold anywhere from 30 BBs to 160 BBs depending on the gun. There is a small spring loaded nub that keeps the BBs from flying out when not in the gun. Once placed into the mag well and clipped into place the bottom of the hop-up unit pushes back the nub and the BBs feed into the unit from the pressure of the spring. All the mags feed the same way so keep this in mind as I go over the other two. The high cap magazine holds hundreds of BBs and is loaded by pouring BBs into a slid door on the top of the mag. You then have to wind a dial on the bottom the turns a spiral spring. There is a wheel inside the mag that is connected to the spring. This will deliver BBs as it turns to the main shaft and up to the hop-up. Each time you fire and a BB feeds up the spring turns the wheel enough to load another BB into the main feeding shaft. The box mag works under the same principal as the high cap. It has its own battery and when the button is pressed the spring is eclectically wound and the BBs are fed into a feeding tub that leads to the hop-up. These mags are big boxes and hold around 2000 BBs. The M249 SAWs use this kind of mag. In short this is what puts BBs into the gun to be fired.

Now that I have gone over each working part of an AEG I will go through a single cycle. You should now have an understanding of what’s happening inside the gun and what each part does.

Pull the trigger and make contact between the two red wire ends. The battery sends power to the motor and the motor turns the pinion gear attached to its shaft. The pinion gear engages the bevel gear which in return rotates the spur and sector gears. The sector gears top partial teeth mesh with the teeth of the piston and begin to pull the piston and spring back. Simultaneously the offset nub on the sector gear starts to pull back the tappet plate and nozzle allowing a single BB to feed into the hop-up unit. The sector gear rotates until the teeth end and the spring pushes the piston forward through the cylinder. By this time the tappet plate and nozzle have returned to their forward position and the nozzle rest against the BB in the hop-up. As the piston moves forward the air inside the cylinder becomes compressed and is forced out the cylinder heads smaller tube. The air travels through the tube and nozzle where it forces the BB out the inner barrel. As the BB begins to move down the barrel it makes contact with the hop-up bucking and starts to spin backwards. The BB exits the end of the barrel and flies to its target, the back spin keeping it from dropping to early.

That’s the firing sequence of an AEG. In full auto this sequence will repeat until the contact is broken between the two ends of the red wire by releasing the trigger.