Any kid who has ever watched Looney Tunes cartoons on a Saturday morning has probably wished for x-ray specs at some point or another—and been horribly disappointed by the fake advertisements for them that show up in some comic books. After all, how cool would it be to be able to see through walls or into things and figure out what’s going on inside? It would make it far easier to assuage curiosity about how stuff works than taking it apart (and making Mom mad when the vacuum no longer works). Fortunately for anyone who has this level of curiosity as an adult, the modular nature of the AR 15 makes it pretty simple to figure out how most of the components work individually and as a comprehensive whole. And, as any AR owner who has customized their firearm can tell you, being able to take apart nearly every little piece of your AR is half the fun.   Form and Function Most of the customization options for the AR 15 fit somewhere in between changing the aesthetics based on personal preferences and making adjustments that affect weight, control, and generally tweak the performance to suit the preferences of the owner. For instance, AR owners can add a handguard rail system to attach hand stops or other accessories that will assist in control and comfort when firing. Or, for a less visible but arguably more impactful change, you could change the length of your barrel or change your gas system.   Why Gas? Part of what makes an AR 15 an AR 15 is the way it functions interiorly, most of which can’t be seen without those x-ray specs we joked about above. One of the primary functionalities of an AR 15 is that it is self-loading in order to make firing more expedient. In order to do this, the AR 15 employs a gas system to help automate the process of firing a cartridge, ejecting the spent casing, and loading another round without additional effort or external steps.   The gas system used in AR 15s makes this process happen internally and smoothly so you don’t have to stop between rounds to clear and reload. And, even better, because the gas system is employed, AR 15s handle all this by capitalizing on internal pressure and inertia so the system is more or less self-contained.     How it Works The gist of it is this: when you pull the trigger to fire, the gas created from primer and powder ignition builds up in the small space between chamber, barrel, bolt face, and bullet/casing. The pressure build-up is what ultimately forces the bullet to move. In a gas system like the one used in most AR 15s, the gas from firing is captured by the system to power the bolt carrier group and cycle the spent cartridge out and the next round into the chamber automatically.   As you customize your AR 15, the right modifications and customizations is going to depend largely on your preferences and primary use for the firearm. For the best AR accessories, shop RailScales online and get the best M-LOK and KeyMod hand stops and rail scales!