Overview of the GBB System Development
by E SHOOTER on Sep 20, 2022
The Development of GBBR
Gas blow back Rifle, which literally refers to rifles, but sometimes it also refers to long guns other than pistols (GBBP). GBBP and GBBR have basically same principles, GBBR's development speed appears to be much slower may be affected by Marui AEG.
In fact, in 1980s, there were also some toy guns which used gas and compressed air for automatic shooting, and the more well-known one was called the BV system.
The BV system was developed by Saburo Aoya, a toy gun designer. BV is short for Bullet Valve, which means that the bullet acts as a valve. As shown in Figure , the BB bullet enters the chamber and blocks it in front of the rubber ring to form a seal, and the chamber pressure rises to a certain level will force BB to shoot through rubber ring.
The structure and principle of the BV system are very simple. Of course, the problem is also obvious. The air supply line directly passes through the BB supply pipe, and the magazine also needs to rely on air pressure to supply the magazine. Because the gas is kept in circulation throughout the whole process, the air consumption of the BV system is very high, and even an external power source is required (for example, connecting a tube to the R134a can), besides, the entire inner tube assembly will reciprocate during BV shooting, so the accuracy is not excellent.
It should be noted that before the appearance of Marui AEG, the BV system was the only toy gun capable of stable automatic shooting. There were still manufacturers launching BV system products in 2007, and a small number of people are still playing it.
In 1993, JAC launched the first GBBR M16A2 (another way of saying it was the M16A1 in 1990)
image source: reddit
JAC's GBB system was designed by Kobayashi Taizo. It adopts a Closed bolt structure like MGC G17. The bolt is not full size, there is no buffer tube structure, and the disassembly is not particularly realistic. The whole is similar to GHK's GBB box (one can A kit to change AEG to Simple GBB).
Image source: Facebook/redwolfairsoft
Like the earliest 93R design ideas, JAC also uses a magazine to accommodate gas and BB bullets. The main body of the magazine is plastic. However, this series of designs are a bit advanced, and the actual quality of the products that can be made at the technology level at that time is not good. It is the magazine that leaks very easily, and it is difficult to find a good JAC magazine nowadays.
There are also different versions of JAC's GBBR. The early one is the same as the JAC G17, which trigger directly pushes the GAS RELEASE VALVE. Later versions used a more stable hammer structure, but it was a special translation hammer instead of the rotating hammer we see now.
The first GBBR with practical value was WA's M4. Till 2008 AEG occupied the mainstream for a long time.
Image source: sayshproject.top
WA has refereed the structure of real guns as much as possible. The receiver thread is AEG specification. GBBR owns a complete and independent bolt at first time , which is closer to the trigger feel of a real gun and a more realistic trigger group.
The WA system was considered the best one at that time. Although it has declined now, many manufacturers are still making WA system products. The leap-forward development of GBBR is after 2010. Such as more new products such as GHK, VFC, viper, etc. . Manufacturers began to invest in research and development, and their system essence was improved from WA's original architecture for better performance.
Although it looks very similar, each system has its own specifications, and there are various differences in details. Of course, there are also cassette trigger group designs such as WE and Marui ZET.
Image source: popularairsoft.com
Compared with the close bolt structure, the open bolt structure needs to push a heavier bolt rear seat, and GBBR has higher requirements for gasification. For example, ZTE, a new design for the low pressure environment of R143a, has inherently superior gasification performance than the WA architecture, but the problem is also obvious, the structure is not realistic...