Mach Sakai makes a comprehensive comparison between two discontinued airsoft guns, the KSC MP9 and the KWA B&T MP9 gas blowbacks. The reviewer highlights differences in their size, weight, and unique design elements, including their non-interchangeable magazines, bolt release mechanisms, sights, and engravings. Performance tests covered trigger pull, magazine release, firing accuracy, muzzle velocity, and sound, revealing distinct characteristics for each model. Though there are some performance issues like blowback and feeding problems during rapid firing, he expresses overall satisfaction with gas blowback airsoft guns.