Taiwan Gun's instructional guide is on how to install and remove airsoft outer barrels for airsoft beginners and budding airsoft techs. It starts with a brief overview of the different types of outer barrels and their lengths. It then goes on to show the step-by-step process of removing an outer barrel from a replica, including how to loosen the screws and remove the barrel nut.

The video also covers how to properly install an outer barrel, including how to tighten the screws and barrel nut. It also shows how to install a barrel extension, which is a common accessory for airsoft replicas.

Finally, it covers some common mistakes that people make when installing and removing airsoft outer barrels. These include not tightening the screws and barrel nut properly, and not using the correct tools. The video concludes with a brief summary of the main points covered.