One the most famous gas blow back airsoft pistol on the market today is Replica of M1911 Variant. Three Major manufacturer ranking from Western Arms, Tokyo Marui & KSC are the most popular choice from airsoft fans.
Western Arms has the most variants of M1911 government models than others thanks to its patented gas blow back mechanism "S.C.W." (SHIBUYA CUSTOM WORKS). A well known draw backs for gas blow back pistol is that its degree of blow back recoil decrease as shots fired through or under cold weather condition because of reduced gas pressure inside the magazine. Western Arms has invested a lot manpower to develop the S.C.W. system that can let gas blow back pistol perform consistantly during cold weather condition. Now the latest version of SCW is version 3 which is sold in our eBay Stores. Most WA's M1911 & its variant has muzzle velocity close to 300FPS (Feet per Second) when shooting under HFC22 (also known as TOP GAS).
Another great choice is Tokyo Marui's M1911A1 Gas Blow Back Airsoft Pistol. It comes with superior craftsmanship & excellent performance. Not long after its release, tons of aftermarket upgrade parts are available from Guarder, Laylax, KM...etc With metal upgrade, this airsoft pistol feel just like the real steel one.
The last to consider would be KSC's M1911 pistol. If you are on budget, KSC is a good choice for you. Although KSC's M1911 is lack of fine detail, it still perform quick well with TOP GAS.
So, let's go shopping