There are two different types of gas guns; the Japanese manufactured ones like Tokyo Marui, Western Arms, and Tanaka and the ones made in Taiwan and China like KJW and KSC. The primary differences between the two are the two types are the materials used in the construction of their parts and the propellant that they use.

The Japanese guns are constructed primarily of plastic composites with few metal parts. The reason behind this is Japanese law that prohibits manufactures from producing metal replica firearms whether or not they are for export. Also, these guns also by law are prohibited from exceeding a propellant velocity more than 1 Joule of energy or approximately 286 feet per second. To accommodate this, the guns use a lower pressure propellant commonly called Japanese Gas or chemically known as HFC134a (a type of Forane gas). Although previously sold separately in the market just for use in Japanese gas guns, customers can actually use PC duster gas like kind found in any electronics store like Best Buy or CompUSA. However, since the duster gas isn’t specifically used for airsoft, the user must add additional silicone to the gun’s moving parts and rubber valves for maintenance purposes approximately every 5-6 magazine fills. Because of the lower pressure gas, the guns receive less abuse through their use and the guns tend to last a little bit longer before regular maintenance is needed. Also because of the general durability of the guns, they are considered the best in the industry and unfortunately carry the price tag with it. (Note: for the Western Arms guns, there is an air flow restrictor that can be placed in the gas chamber in the upper receiver that allows them to fire green gas. However because the modification requires the cutting of a certain piece, the modification is irreversible without an entirely new chamber. Do not attempt unless you know what you are doing or are sure that you want the modification to be final.)

Taiwanese and Chinese guns run on the other side of the spectrum. The parts manufactured with steel or aluminum depending on the particular model of gun. Because of the strength of the products, Chinese and Taiwanese guns are able to shoot at a higher velocity. The propellant recommended and manufactured for these guns is known as Green Gas, Top Gas, or Taiwanese Gas. The chemical construction of the gas is propane mixed with 100% silicone for lubrication. Because of reinforcement of laws by the Department of Transportation concerning the shipping of hazardous materials, it is now much more difficult to ship Green Gas without paying a hefty HAZMAT fee. An option for Green Gas users is to get a propane adaptor such as the ones produced by Airsoft Innovations or Mad Bull (won't work with KWA M-11 gun) and attach it to a camping propane bottle found at any outdoors store. The advantage of this is that it is significantly cheaper in the long run since most bottle of propane can be bought for less than three dollars. The disadvantage is that regular propane is spectacular at drying metal and rubber parts, so the magazines, gun slides, rubber parts, and the propane adaptor itself must receive an application of silicone approximately every 5-6 magazine fills or risk a build up friction and degradation of rubber pieces.

Gas Magazines (Maintenance and Use)

If used correctly and maintained with silicone often, gas gun magazines can be expected to function well for many years. To fill a gas magazine is easy. To fill the magazine hold the gas bottle inverted with the filler tip down in one hand with the magazine in the other hand. Position the filler tip of the bottle into the filler valve of the magazine. While holding the two below eye level (preferably around mid chest for safety reasons), firmly insert the tip into the valve. For the smaller magazines like the standard ones found in sniper rifles, shotguns, and pistols, hold the two together for approximately 3 seconds (One-one thousand… Two-one thousand… Three-one thousand), for a complete fill. For the larger ones like the extended magazine for the KWA G-series pistols, Beretta pistols, and the magazine on the KWA Mac-11 machine pistol, take about 5 seconds to fill them since they have a larger capacity and therefore need more propellant. However, be careful not over-pressurize the magazines since it puts undue strain upon its internals and valves potentially causing damage. Although Green Gas already has silicone premixed into it, it is recommended to lubricate the rubber valve on top of the magazine and in the slide (upper receiver) with 100% silicone every 10 magazine fills. If you are using duster gas or propane it is recommended to lubricate the valve every 5 fills. After the completion of the day or when the magazines/ guns are not in use leave a little of gas in the magazine so that just enough pressure remains on the seals to keep them tight.