I'd like to thank Villain for reminding me about this...I re-wrote this in order to make it more accurate ages ago and never re-posted!
Keep in mind, this is not purely objective, I have opinions in here, take my opinions and the opinions of others with a grain of salt, this is a basic guide, once again, feel free to fix it up if you see fit, or add. Also much stated here as fact has not been widely confirmed, much is based on other forums that I read and I post others results. I wish I had saved sources for most of this, but alas it has come from the vast corners of the intarwebz.
Airsoft Acronyms
TM - Tokyo Marui
CA - Classic Army
E1 - Echo 1
DB- Dboys
JG - Jing Gong
WA - Western Arms
KJW - KJ Works (not sure what the KJ stands for)
MAN - Montgomeryville Army Navy
ASGI - Airsoft GI
AEG - Automatic Electric Gun
AOE - Angle of Engagement
ROF - Rate of Fire
FPS - Feet per Second
Hop Up Bucking- the part that puts back spin on the BB.(Also known as packing, hop-up rubber, etc.) Marui guns come with decent ones but other companies make better ones. Systema, Guarder, Prometheus and Fire Fly all make fairly decent buckings. Fire Fly makes a special one with 3 nubs in the bottom to create a better spin, and they are my preferred brand.
There are types of bucking...
Soft - used for guns shooting lower than 400 fps, softer rubber means more spin
Hard - used for guns shooting over 400 fps, harder rubber is more durable and wont tear as easily from high velocity BBs, but it also wont have as much of an effect
Medium - a few brands offer this kind of bucking, I suggest using it if your gun shoots around 380-399 fps, ONLY if a soft bucking has already ripped from the BB being to fast, like I mentioned, you want the softest bucking you can use.
Hop Up Chamber - The Hop Up Chamber houses the end tip of the barrel, bucking, and nubbing. Essentially the chamber has an adjustable arm that pushes a little plastic "nub" into the bucking, which in turn pushes the bucking into the barrel which allows the BB to come in contact with the rubber, putting spin on the BB. Some companies offer after market chambers, a new chamber is not necessary unless you are having problems with your stock chamber. Also there is no major difference from a plastic and metal chamber other than the metal one being less likely to break, but a broken chamber is RARE!
Nub - Also called nubbing/nubbin*, nubs, spacer, or buffer rubber. The nub sits on the end of an arm that is in your hop up chamber. When you adjust your hop up the arm either pushes down or pulls up from the nub, resulting or more or less hop-up.
There are different kinds of nubs...
Basic Nub - I trust this kind the most, it is essentially just a circular piece of rubber that pushes down on the bucking, they vary in terms of hardness, you want a nub that isn't too soft or too hard, a hard one will slow the BB down while a soft one will have limited effect on the spin of the BB.
H-Nub - Supposedly puts pressure on TWO points of the BB, making the BB have a more accurate trajectory.
SCS Nub - Considered the "best" nub you can get, I have tried it and disliked it. It did nothing but slow my BB down. (The science behind it is nice, it just simply does not work how it is supposed to though when I had used it. I believe Jon did not have good results when he tried it either)
Barrel - Some people change to barrels longer or tighter than their stock ones. The tighter the barrel the more FPS you will get due to less air escaping around the BB. Most AEGs come stock with 6.08mm diameter barrels. Systema makes a 6.04mm, Star makes a 6.05mm, Guarder makes a 6.04mm, Prometheus makes a 6.03mm, Deepfire makes a 6.04mm, Madbull makes a 6.03mm and just recently started making a 6.01 mm and PDI makes the best 6.01mm from steel.
Internal smoothness and diameter consistency is also an important factor.
NOTE - The tighter bore your barrel is, the more anal you have to be about your BBs and barrel cleanliness. A dirty tight bore will clog with dirt more easily causing a jam, and BBs that aren't perfect 6mm spheres will also jam, potentially breaking the barrel or air nozzle, worst case scenario you could break your barrel, hop-up, air nozzle, and potentially even your internals! DON'T CHEAP OUT WITH BBs AND CLEAN YOUR DAMN GUN!
Spring - The stronger your spring, the higher the velocity the piston can be forced forward at. Don't fit a high powered spring with standard internals as you are likely to damage the gears or piston. PDI springs are my favorite due to their universal ranking system*. Most springs besides PDI are rated in meters per second, so a M100 spring is 100 meters per second or 328 feet per second. (One Joule)
*PDI RANKING SYSTEM: PDI rates their springs on a percentage system, 100% means your gun will shoot at 100% the power of a Tokyo Marui airsoft gun, or ~260 fps. THEREFORE a 150% spring would be 150% the power of a TM gun which would be ~350-400FPS
My favorite spring is the PDI 150%, it is high tension enough to get the range you want without hurting people and is field legal at ALL C3 fields. It also isn't so high tension that you have to upgrade your gearbox to use it! (most likely)
Spring Guide - This stops the spring from jumping into the gear case.TM guns come with plastic guides as standard, if you are going to upgrade the spring on a TM get a metal spring guide. Some companies offer spring guides with ball bearings, these will reduce the strain on your gearbox, DO NOT USE A BALL BEARING GUIDE WITH A GUN SHOOTING OVER 450FPS, THE BEARINGS MAY FAIL!
Cylinder - The cylinder is the area in which the air is compressed before being forced down the barrel. Bigger cylinders let you use a longer barrel. You can also get Teflon-coated cylinders which will give a slight increase of ROF. This part isn't upgraded much as most guns come with good ones. For a budget gun one get a Teflon coated Area 1000 cylinder.
NOTE*
For guns where the barrel is less than 455mm long, YOU NEED A PORTED CYLINDER! You have to make sure you match your inner barrel with your cylinder to regulate the air pressure. You might see a drop in fps, but it isn't going to be anything significant in performance. You will see poor performance with a non ported cylinder matched with a short barrel, like an MP5. Since there is more air pressure in the cylinder the BB leaves the barrel before the piston actually reaches all the way to the end of the cylinder head. So your BB is actually out in the air before the piston even finishes its cycle, you may as well be blowing down your barrel!
Cylinder Head - Changing this part will either silence the air flow of your gun, if you buy a silenced cylinder head and use it in conjunction with a silenced piston head. OR increase air compression, for example switching from a single O-ring cylinder head to a double one would most likely increase compression.
Air Nozzle - The air nozzle is the part that pushes the BB into the Hop Up Chamber and guides the air into the barrel, or seal the airflow from the cylinder head to the BB, so some have internal 'O' rings like Guarder.
There is also a modification where you can add an external O-ring, I have heard good things about it but have never tried it, if you are up for experimenting you can try it out
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Piston - The piston compresses the air in the cylinder. It is essentially a flat-toothed gear. It is wound back by the motor and then forced forward at high speed by the spring, compressing the air in front of it. It therefore is subject to tremendous pressure. Metal pistons are good for Semi-Auto AEGs but if fired in Full Auto they may strip the gears. The Super Core Piston made by System (not to be confused with Systema) is the strongest of them all...however many polycarbonate pistons have been proven to be just as strong and much cheaper.
There are also three mods that can be done to a piston...
1)
AOE Mod - Probably one of the most useful piston mods, the AOE mod helps prevent piston breaking by increasing the amount of area the piston engages with on the sector gear, meaning there is less a chance of piston teeth being stripped by the sector gear. The mod involves putting pads/washers, really anything between the piston head and piston that can expand the length of the piston. The only draw back to the AOE mod is that you lose about 10-20 FPS due to the piston being moved further into the cylinder meaning less air is compressed.
2)
"Swiss Cheesing" - Swiss cheesing involves using a Dremel to cut out all non essential parts of the piston, thus reducing the weight of the piston increasing your ROF. A risky mod if performed incorrectly, can lead to pistons shattering. Apparent good results if you have a steady hand and know what you are doing, I wouldn't do this on your primary, or if you have a high FPS set up
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3)
Short Stroking - Involves removing first two or three rear teeth of the piston (they aren't needed for a piston to complete its cycle) this increases the ROF and can also prevent pistons from breaking on a high ROF set up, as high ROF guns (usually) grind the rear to teeth off the piston anyway
Piston Head - The piston head seals the air into the cylinder. You can get good and bad ones. Classic Army and most clones generally have poor piston heads. You can also get silent ones to quiet the air flow of your gun, as well as bearing ones which when used in conjunction with a bearing spring guide can also decrease the stress on your gearbox.
Two kinds of piston heads...
1)
Polycarbonate Piston Heads - put less stress on the gearbox which is needed in a high FPS set up (500+ FPS), contributes to the distinct sewing machine sound of an AEG. MUST USE A POLYCARB PISTON HEAD IF YOU USE A TEFLON CYLINDER!
2) Metal Piston Heads - generally produce a louder more distinct sound than polycarb piston heads
Gears - The gears are a very important and expensive part of the rifle. Don't be tempted to buy cheap gears, as you will probably end up paying a lot more to fix the gearbox when they break. If you are upgrading to high powered springs or hi-speed/torque motors get for steel gears. If you want high ROF you can buy high speed gears from Prometheus, Systema and Guarder. Systema, Guarder and Prometheus make high torque as well. Most of these are helical which means the teeth are at an angle. If you use these you need a half toothed piston. They are also harder to shim correctly. You have 3 gears, the sector, bevel and spur gears.
Modify makes AMAZING modular gearsets, in both high torque (for 400+ FPS) and highspeed sets. Their sets are practically indestructable and perform very well, not to mention they are preshimmed, have built in stainless steel bushings, and are correctly timed. They are also are bracketed together, takes the work out of gear installation, and you are guaranteed to get maximum speed and efficiency out of your gun!
Pinion Gear - This gear is attached to the motor and is what drives your gear set. This gear commonly strips ESPECIALLY in a high ROF set-up or if gears are shimmed improperly. THIS GEAR CANNOT BE CHANGE WITHOUT A PINION GEAR REMOVER! YOU WILL BREAK YOUR MOTOR PERMANENTLY IF YOU TRY TO REMOVE THIS GEAR WITHOUT THE PROPER TOOL!
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Bushings - The bushings keep the gears in places and are what the gears rotate on. If they break the gears will probably strip. The bigger the bushing the better. Most guns ship with plastic 6mm bushes fitted. If you upgrade go for metal bushes and if you are looking for higher ROF or torque, get a new gearbox casing that will take 7mm or 8mm bushes.
TM has nylon bushings stock, while those perform great for the low FPS stock set ups, they will break if you upgrade ANYTHING in your gun that will increase the torque on the gears, CHANGE THEM TO STAINLESS STEEL!
Shims - The shims are used to keep the gears aligned and correctly meshing. Incorrect shimming will lead to increased gear wear or failure. Guarder makes good shims.
http://www.arniesairsoft.co.uk/?filn...Fshimguide.htm <-- Great baseline for shimming
NOTE* You should re-shim your gears EVERY TIME you open your gearbox and change anything, it is a great precaution! Remember, measure twice cut once, ALWAYS BE PATIENT when shimming gears, it will save you time and money in the long run.
Tappet Plate - pulls the air nozzle back to let the BB in. If it snaps your gun will not feed. TM stock and ANGEL are supposedly good, but don't go replacing your tappet plate unless yours is already broken. Changing your tappet plate won't increase performance, just reliability if anything at all.
SCARS have notorious tappet plate failures though, so you may want to replace those BEFORE they break.
Anti-Reversal Latch - This latch stops the gears from spinning backwards and damaging the gun. Systema and Prometheus make aftermarket versions, most stock latches are fine however. BE SURE TO SET THIS LATCH IN PLACE IF YOU ARE OPENING YOUR GEARBOX!
Cut off Lever - This stops the gears so you can fire Semi-Auto. If it does break or wear you will only have Automatic fire.
Sector Chip - Guns don't come stock with these but they essentially keep the tappet plate back longer so the BBs feed better. They have no negative side effects and will not break.
Motor - You can opt for hi-speed or torque. Don't put a hugely powerful motor in a standard gun and hope it will work. You will strip the gears or piston. The Systema Magnum and Turbo are excellent. Classic Army high torque motors are also fairly good. TM also has a wonderful motor known as the EG1000, probably the best motor for the money.
Lubing - Lubing is easy and essential! Using white lithium grease liberally coat your gears with a thin layer of it, then using a silicon based grease (not spray) put a thin layer, about 1mm thick on the inside of your cylinder and with a q-tip lubricate the piston rails and ALL O-rings in your gun with a tiny bit of silicon grease
Battery - The higher the voltage, the higher your ROF will be. The higher the Milliampere-Hour rating (mAH), the more BBs you can fire per charge (as a rule of thumb for a fairly standard gun, 1 mAH = 1 shot). Intellect and Elite are great. Most chinese guns come with poor batteries. Do not go for the highest power battery you can find straight away, as the voltage may be too high for your current setup and may damage components. 12volt = really high ROF and electrical demands. Many guns even upgraded cannot handle these batteries.
Batteries with too great voltage can lead to...
Electrical Damage - Higher voltage means more power, more power means more energy, more energy means more heat, you follow? Say I throw a 20v battery in my gun, here is what will likely happen...
1) The battery melts
2) The connector melts
3) The wiring melts
4) The solder melts
5) The trigger assembly melts (place where the current jumps from copper connector to motor, essentially telling your gun when to shoot)
Notice the pattern? DON'T OVERDUE YOUR VOLTAGE!
Gear Wear - Higher voltage means higher ROF. A higher ROF set up will lead to more wear on your gears and piston. You have no room for error on a gun shooting fast, do everything right the first time or get ready to spend money if you got a high ROF set-up.
BBs - Good BBs are essential, bad BBs will break your gun faster than you can say LOLOLOLOLOLOLOLOL! As a test of BB quality, take a pair of needle nose pliers and try to crush the BB. You can get a sense of the BBs construction based on how it crushes, also avoid BBs with noticeable air-bubbles or seams.
There are a few brands I trust, all these BBs should work fine and never fail you (listed in my opinion, greatest to worst)
1) Goldenball, never had an issue with them, they are the smoothest most perfectly crafted BBs I have ever seen
2) Airsoft Elite, pretty much in the same boat as Goldenball, easier to find though
3) KSC - good BBs for a good price
4) Firepower - again, good BBs for a good price, easy to find
I have heard that the new King Arms BBs that have just been released are quite good too, MAN carries them for a good price
BRANDS NOT TO TRUST
- Crosman
- ANY .12g BBs
- Did I mention Crosman?
- Anything you can find at Walmart
Sources for DIY Repair/Upgrading
http://mechbox.com/
http://pageproducer.arczip.com/daedalus03/workshop.html
My Favorite Retailers
East Coast
http://montarmynavy.com/ <-- Local PA store, you should all know about it already
http://trinityairsoft.com/
http://shortyusa.com/
http://airsoftatlanta.com/ <-- My favorite online airsoft store
http://cheapbatterypacks.com/ <--- great for custom batteries and cables
West Coast
http://AirsoftGI.com/ <-- Not the greatest customer service and terrible shipping, they do carry A LOT though
http://Evike.com/ <-- Sort of in the same boat of ASGI, a bit better
http://Airsoftextreme.com/ <-- Great retailer, also sponsors of C3
http://militaryclothing.com/ <-- very cheap site to buy your clothing from, not a bad selection of boots either
http://uscav.com/ <--- another good tac gear site
International
http://redwolfairsoft.com/ (pay with paypal internationally, makes things easier)
http://www.ratech.com.tw/eng_ra/intro.php <-- great GBBR parts
http://shop.ehobbyasia.com/
