Gae Bong Soon does a comparison of the popular Action Army gas blowback pistol pistols, the AAP-01 and AAP-01C gas blowback pistols. The AAP-01, which is based on the Ruger MKIV, is available in black or dark earth colors and is made of polymer except for the aluminum bolt, bolt release, and frame pins. Each model has an end cap that protects the polymer 14mm CCW thread on the barrel end, allowing most suppressors and tracer units to be fitted without the risk of warping the outer barrel or causing friction on the blowback like most GBB pistols.