There is an excellent variety of airsoft pistols available to the airsoft enthusiast. Anyone seeking to expand their inventory would have no problem finding the right gun. There are of course the three main types of airsoft pistol: gas, electric and spring.
Airsoft gas pistols are further divided into categories of propulsion. You can either have CO2 or Green Gas. Green Gas is HFC22 and is more powerful than HFC134a. There are some pistols that can use both as interchangeable propulsions. However, a user needs to be aware that some pistols are HFC134a only. You could possibly damage your gun if it is specifically designed for HFC134a use. Check the specifications of the gun you choose before buying gas cartridges here at www.kjworks.com.tw/main.php
Electric airsoft pistols are definitely easier on the user end by simply using batteries. Many of the pistols available run on AAA batteries, but there are a few that run on larger, rechargeable batteries. Electric pistols perform well but do have a slightly reduced velocity. The obvious requirement when considering an electric pistol is having extra batteries and fully charged backup battery packs.
Spring loaded airsoft pistols do not necessarily drop off much in terms of velocity and performance. In fact a spring pistol means never having to reload gas cartridges, swap out or recharge batteries. These pistols are simple and only require the added labor of pulling the slide back. While the added movements of cocking the gun seem like a down side, most users will find the difference in propulsion a non issue when talking about a secondary side arm.
Even when you have narrowed down which type of pistol you are looking for, you still have a lot of style options available.